A summary of many years’ experience in prepress typesetting design of printing plants
First, image processing Pictures play an important role in newspaper layout. If used properly, they can not only beautify the layout, increase people’s reading interest, but also make the finishing point. The processing of a picture before printing directly affects the effect after printing. Therefore, through practice, I have made some useful explorations on image processing.
Before processing a picture, you should look at it first. The quality of the picture should be well known, that is, whether the exposure of the picture is excessive or insufficient, whether it needs to go to the net, etc., so that the picture can be properly operated in the process of processing, and the loss of hierarchy can be minimized.
In Photoshop processing pictures, the black and white field and gray balance must be determined first, which are very important and necessary. According to different printing needs, the determination of black and white fields is different. But the standard is that the black field can’t paste the white field and can’t cut off the net. However, in order to ensure a better visual effect after printing, a small area of net or paste can be considered, but it must not be a large area. If the picture is distorted, we can restore its color through gray balance, but moderate gray affects the color of the whole picture, so use it accurately. There are several experiences in mastering gray balance, that is, below 20% or above 80%, CMY values are basically the same; In the middle part, MY values are basically the same, but c values are 10 ~ 15% higher than MY values.
In practice, the processing of gray scale map will be relatively simple. There are two ways to exchange color images into grayscale images: directly use the “mode” function for conversion; Or first convert the color image into Lab mode, then delete “a channel” and “b channel”, and finally convert the image into & “gray scale”. In the chroma Lab mode conversion, the L channel of brightness keeps more hierarchical changes, so the effect will be better. After setting the black-and-white field of gray-scale picture, we should pay attention to the level of the picture, and the middle tone must be opened, otherwise the picture will feel foggy, dirty and unclear. Increasing the contrast of the middle tone will obviously improve this situation In the process of using Photoshop to process pictures, don’t let the pictures turn around in two modes. Because, every time a conversion is made, a part of the details of the original picture will be lost. When converting RGB mode pictures into CMYK mode pictures, color separation parameters will play a decisive role in the effect of picture conversion. The adjustment of color separation parameters will affect the conversion of pictures to a great extent. Photoshop image processing software has the ability to control color separation parameters, that is to say, when the image processed in RGB mode needs to be converted into CMYK mode for output, the color loss during the mode conversion can be alleviated by adjusting the color separation parameters during the conversion process.
If the RGB mode picture is converted into CMYK mode, an intermediate step is added to the operation steps, that is, it is converted into Lab mode first. Lab mode consists of three channels, L channel represents brightness, which controls the brightness and contrast of pictures, A channel includes colors ranging from dark green (low brightness value) to gray (medium brightness value) to bright pink (high brightness value), and B channel includes colors ranging from bright blue (low brightness value) to gray to focal yellow (high brightness value).
Lab mode is similar to RGB mode, and the mixture of colors will produce brighter colors. Only the value of brightness channel affects the change of color. The Lab mode can be regarded as the RGB mode of two channels plus the mode of one brightness channel. Lab mode is independent of equipment, and can be used to edit and process any picture (including grayscale picture), and it is as fast as RGB mode, but several times faster than CMYK mode. Lab mode can ensure that there is no loss of color in CMYK range during color mode conversion. Processing pictures in different modes will have different effects. For example, Lab mode is very helpful to increase the contrast of pictures, but the use range should not be too large, otherwise the pictures will be distorted. RGB is the best mode for processing pictures. It provides the saturation and brightness of photos, and has good functions such as expressing levels. It is especially good at adjusting people’s facial colors without causing distortion or loss of levels. Only all pictures have to be converted into CMYK mode before printing, so adjusting pictures in CMYK mode has advantages. In this mode, adjusting each color through channels can prevent the color cast of pictures, and it is also convenient to determine black and white fields.
Different pictures need different processing methods. Pictures like traditional Chinese painting must be faithful to the original film, and its color cannot be changed because of its good effect. Pictures such as comics and calligraphy can not be lost in detail, but also consider using bitmaps, which are clear and have small image capacity, which will improve the speed of hair distribution.
In addition, there are many practical tools in “Image Adjustment” in Photoshop, such as “Brightness/Contrast”, “Hue/Saturation”, “Optional Color”, etc. In practical work, as long as they are used reasonably, they will get good results. Next, I will explain them one by one.
Below I mainly talk about the online image processing. Some pictures on the internet are often used in oilfield newspapers, such as Hanhai, which are various, but not every photo can be used. Pay attention to when choosing online photos:
1, try to choose some contrast, contrast photos.
Due to the limitation of printing conditions, newspapers generally have coarse mesh, and lose some layers when they hang up the net. However, online pictures are basically small and poor in layer performance, so printing after photos are too rich can’t be expressed. For example, some photos after sunset are rich in layers and beautiful on the display. After printing, you will find that the photos are not beautiful because of faults; However, some photos with great contrast and contrast have a weak sense of hierarchy and no fault.
2. When using photos of online characters, choose some panoramic or medium-sized photos, and use less close-ups.
Most people are very sensitive to the faces of the characters in the pictures, so close-up photos of the characters’ faces require high levels of clarity. If the photo is too small to express, after printing, it will be found that the face colors of the characters are patches, and it is easy for readers to feel that the quality of the picture is not good enough. In some panoramic or medium-sized photos, the characters’ faces are very small, which focuses on the characters’ movements, so that the readers ignore some details, and the photos can be careless.
3. Use less or no online charts.
The content of the chart is intuitive, and editors like to use it. However, the text in the chart is of poor quality after being expressed in the picture format, which will basically appear jagged, so that readers can’t see the content clearly. If charts must be used, it is suggested that the editor should ask the image processor to remove the text and replant the text block into the picture when typesetting. It’s called re-charting.
The biggest difference between online pictures and photographers’ works lies in the size of pictures, which can be said to determine the quality of printed pictures.
Generally speaking, the size of picture file is directly proportional to the size of picture layout in newspaper. Because of the network speed and other issues, online pictures are mostly in JPG format, and the file size is usually only tens of K or even dozens of K or a few K (for convenience of uploading, general websites will be limited); Now, digital camera works are also saved in JPG format, with 3 million pixels and medium precision photography, and the file size is also hundreds of K. If an online picture wants to be used in newspapers, it is generally required that the photo file must be larger than 20 K, and the photo size in newspapers should be within 6×10 cm; In other words, the size of the online picture when used on the layout should be the original size (after the resolution is changed to 200 dpi), and it should not be enlarged by more than 120%, so that the image quality will not be poor when printed. Of course, the bigger it is, the less likely it is to be distorted.
Processing problems of online pictures: Online pictures and photographers’ works are basically handled in the same way, but the degree choice is different, and the requirements for photo adjustment are higher. The processing of some details can often determine the final printing quality.
1. be sure to save pictures in TIFF or EPS format.
Most of the pictures on the Internet are in JPG format, which takes up less system resources and is fast, and it is also indispensable for printed materials with low accuracy requirements such as newspapers. However, JPG is a picture saving format that impairs the compression algorithm, and some data will be lost every time an image is saved, which is a disaster for online pictures with little picture information. However, TIFF or EPS format does not have this situation. Therefore, we require image processors to get used to using TIFF or EPS format when saving pictures, and they can reprocess pictures many times.
2. Processing pictures in RGB mode and saving pictures in CMYK mode When a color picture is opened, it may be in rgb mode or cmyk mode. So when using photoshop, do you use rgb mode or cmyk mode for color picture processing? Let me talk about my own views.
In the process of using photoshop to process pictures, first of all, we should pay attention to the fact that for an opened picture, no matter which mode it is, don’t turn around the two modes. If a picture is converted into rgb mode and cmyk mode for a while, the information loss of the picture will be great. It should be said here that the picture mode used for plate-making printing in the process of publishing color newspapers must be cmyk pictures, otherwise printing will not be possible. But it doesn’t mean that the printing effect of processing pictures in cmyk mode will be very good, or it should be decided according to the situation. In fact, the effect of using photoshop to process pictures in rgb mode is stronger than that of using cmyk mode. As long as the pictures are processed in rgb mode, they can be converted into cmyk mode pictures and then output to film for plate making and printing.
When converting rgb mode pictures into cmyk mode pictures, color separation parameters will play a decisive role in the effect of picture conversion. The adjustment of color separation parameters will affect the image conversion to a great extent, and photoshop image processing software has the ability to control the color separation parameters. That is to say, when the picture processed in rgb mode needs to be converted into cmyk mode for output, the color loss of the picture during mode conversion can be alleviated by adjusting the color separation parameters in the conversion process. In the process of operation, we should pay attention to: the pictures processed in rgb mode must ensure the authenticity of the picture color when output in cmyk mode; When using rgb mode to process pictures, make sure that the pictures have been completely processed before being converted into cmyk mode pictures. It is best to leave a picture in rgb mode for standby.
3. Sharpening adjustment of picture definition.
Insufficient emphasis on sharpness (sharpening), unclear outline, blurred picture: too much emphasis on sharpness, and stiff outline of picture. The quality of picture is directly affected by the quality of definition control. Online pictures are usually low in accuracy, indistinct in level and easy to blur. Therefore, sharpening is by no means an optional process, but a necessary part of online picture prepress processing and the most effective means to improve image clarity. For different types of pictures, it is necessary to find out the appropriate sharpening level from practice. From the display screen effect, the sharpening degree of people’s pictures is usually too good, and for some landscape pictures, it can be bigger.
4. Adjust the levels and colors of online pictures.
The purpose of level adjustment should first meet the printing requirements, and concentrate the main level in the middle area, that is, 20%~60% of the visually sensitive area. Secondly, according to the original content and level distribution, ensure the accuracy of important parts, such as clothes and face; Thirdly, it is necessary to adjust the value of extremely high light or dark tone, and do not cut off the network in a large area, which is generally controlled at about 2% ~ 95%. The color adjustment of online pictures is mainly to keep in mind the 3% ~ 5% gray scale of newsprint and adjust some dim pictures to be brighter and brighter.
5. Make proper use of filters in photoshop.
Photoshop is an international professional-grade image processing software, which has already been widely used in China. Some of its filters use the interpolation method to enlarge and compensate images, which can increase the resolution and size of a small picture. Online pictures can also be properly used for practical needs. However, this Intellihance filter can’t increase the level and color of the picture. It only makes it convenient for the image processor, and can’t pin their hopes on it. There are also some special image magnification compensation software, such as S-spline, which have similar functions.
However, I personally think that online pictures should not be used or used as little as possible in newspaper pictures, but if they are often used in practical work, as long as they are properly selected and carefully handled, online pictures can also play a role in newspapers. However, there will be various situations when printing, so we should adjust our work according to the characteristics of the printing press downstairs. The red header is generally MY100, the earth, but the skin color is shallow net, and the two are in conflict. If the ink is big, the skin color will definitely be burnt, and if the ink is small, the red header will not be so red. Therefore, this situation is rather difficult. Generally, in order to take care of the color of the header, the skin color will be ignored. Therefore, color cast.
The most important parts of character picture reproduction are facial skin color and other exposed parts of the body, such as hands, feet and legs, etc., and facial skin color becomes the most important thing. When looking up data on the Internet, someone summed up and found the rules shown in the following table.
(1) The color ratio of facial skin color is as follows: C: below 10%; M: below 25%; Y: below 35%; K：0%； And the proportion of y is slightly more than that of m, so the printed pictures at this time are more white skin color, and are mostly photos taken under better light conditions and better location selection, such as photos taken under strong light.
(2) C: less than 15%; M：25%-35%； Y：35%-45%； K：0%； In such a range, when the proportion of Y is slightly more than about 10% of M, the printed facial skin color of the characters is very close to that of our Oriental people, with clear hierarchy and ideal effect. On the contrary, in this range, if the proportion of M is close to the value of Y, or the value of M is more than 5%, the printed skin color is slightly pink, which is still a good picture because of its hierarchy and clarity.
(3) C: less than 15%; M：35%-50%； Y：45%-60%； K：0%； This kind of picture has high requirements for printing operators. In the printing process, the post-press process can reproduce the original effect of the picture when the balance of ink and wash is well controlled, but it is prone to color deviation. Because magenta has strong color rendering, it is easy to turn red and difficult to control.
(4) C: less than 15%; M: more than 50%; Y: over 60%; K：0%； In this case, no matter how the printing operator controls it, it is difficult to get ideal results. The printed pictures are prone to two problems: one is reddish, the other is unclear and boring.
(5) Pre-press process according to the three situations in Table 5, 6 and 7 above, C: 15%-25%; K value is no longer 0, and most of them are shot in relatively dark places. If M and Y components are relatively small, it is easy to be slightly cyan when printed, and if M and Y components are heavy, it is slightly black. At this time, printing operators are also required to achieve good ink balance control in the printing process, and can reproduce the original color normally.
(6) C: more than 25%, at this time, K value also has a certain proportion, which is some pictures with darker skin.
(7) C: less than 15%; M: below M：35; Y: over 60%; K：0%； At this time, the printed pictures are still acceptable from a distance, slightly yellowish, but after careful observation, it is found that the level is slightly deficient. For example, when we are printing some pictures taken indoors at night, because the indoor lights are generally yellowish, the color of the characters is generally heavier in their special lighting environment.
From the above table, the best color hierarchy ratio of Oriental skin color in newsprint printing is the first two cases, that is, C: below 10%; M: within 35%; Y: within 45%; K：0%； Even if the proportion is slightly heavier, the composition of M should not exceed 50%, and the composition of C should not exceed 25%. For black people, the C and K components are slightly heavier, but they should also be in a relatively low range. It is also reasonable to analyze the characteristics of newsprint printing. Because of its rough surface, low sizing degree or no sizing typesetting, loose structure, serious dot expansion, and easy occurrence of grading and paste death, the reproduction of layers is far inferior to offset paper and coated paper. The dot expansion is small at 0-30% and 70%-100%, but the dot expansion can be achieved at the middle adjustment, especially at 50% In my opinion, when choosing prepress pictures, we can’t only rely on the visual effect on the screen, because if the display is color-biased without color correction, it is best to read most of the CMYK values of its face and skin color in PHOTOSHOP software with INFO tools, and most of them are within the aforementioned range. Such pictures create conditions for post-process printing. On the contrary, if they exceed the aforementioned range, they need to be greatly adjusted to reach the standard as far as possible.
Let me briefly talk about several tools commonly used in processing pictures in PS:
Curve tool Curve is also one of the most important commands for image adjustment. After the histogram of an image is normal, curve is needed to make fine adjustment. The purpose of curve adjustment of 1234 points: one point changes the shade; Two points control image contrast; Three points improve the dark level; Four points produce hue separation.
The right curve can light up the picture!
Down, the picture darkens!
You can adjust the contrast of the image at two points Below I use a photo example to illustrate the whole process of adjusting photos:
Get a photo, preview it first, know the whole picture, pay attention to a whole beauty, and then highlight the part of the photo that you want to highlight. Both background and characters pursue unity. Be patient when dealing with it, and try different ways to color it until you are satisfied.
Let’s talk about it step by step, which is very common: open the original image with Photoshop (I use CS3, but other versions are similar). First, look at the whole photo. Most of the ordinary photos come from ordinary digital cameras and specific scenes, and the black and white fields can’t be well positioned, so the photos will be gray like this one.
First copy a layer of background to avoid misoperation, keep the original film, and perform: filter > sharpening > USM sharpening. The value depends on the size of the photo. This step is very necessary Create a level adjustment layer. The number of highlights is on the right, the number of dark tones is on the left, and the middle tone is in the middle. Sometimes the exaggerated PS technique can be adjusted harshly, mainly depending on the need of expression. Here, I just want to use this color scale to increase the brightness of the face, and pull the rightmost adjusting lever until the face starts to have the phenomenon of high gloss overflow, that is, I feel a little too bright. Don’t move the left and middle ones, then press OK.
Next, a key step is to create a color balance adjustment layer, so that the adjustment will make the photo as a whole turn cyan and set off the face.
To enhance the contrast, create a new black-and-white adjustment layer, select “High Contrast Red Filter”, and confirm.
The photo at the moment looks very strange. Don’t worry, let’s change the mixing mode to “soft light” and reduce the opacity to 70% (it depends) At this time, the photos are already very nice, but they are very pale, so we add a hue/saturation adjustment layer with a saturation of +15.
At this point, the whole has been dealt with almost, and the rest is the details. The specific tool used is the pen tool. I’ll be brief.
Photoshop’s pen path is a very important modeling tool. After you click a point on the adjustment path, press the “Alt” key, then click with the left mouse button, then one of the “adjustment lines” will disappear, and it will not be affected when you click the next path point.
If you draw a Path with “path” and the mouse is now a pen, you only press the Enter key on the keypad (remember that it is the Enter key on the keypad, not on the main keyboard), and the path will immediately become a “selection area”.
If you draw a path with the pen tool, and the state of your mouse is pen now, just press the Enter key on the keypad (remember that it is the Enter key on the keypad, not the main keyboard! ), the path is immediately loaded as a selection.
Click the mouse on the trash can icon on the path control panel after holding down the Alt key to delete the path directly.
While using other tools of path, hold down the Ctrl key to temporarily change the cursor to the direction selection tool.
Click the mouse on the trash can icon on the path control panel after holding down the Alt key to delete the path directly.
While using other tools of path, hold down the Ctrl key to temporarily change the cursor to the direction selection tool.
Click the blank area on the path panel to turn off the display of all paths.
When you click several buttons at the bottom of the path panel (fill the path with foreground color, stroke the path with foreground color, and load the path as a selection), you can see a series of available tools or options by holding down the Alt key.
If we need to move the whole path or multiple paths, please select the path to be moved and then use the shortcut Ctrl+T to drag the path to any position.
This is the use skill of several pens, and the specific operation should be mastered in practice.
PS shortcut keys! Must master!
Toolbox (if multiple tools share a shortcut key, you can press [Shift] and add this shortcut key at the same time) Rectangular and elliptical box selection tool [M] Cutting tool [C] Moving tool [v] Lasso, polygonal lasso, magnetic lasso [L] Magic wand tool [w] Gun tool [j] Brush tool [b] Like leather stamp and pattern stamp [S] History Brush Tool [Y] Eraser tool [e] Pencil, linear tool [n] Blur, sharpen and smear tools [R] Fading, deepening and sponge tools [O] Pen, free pen, magnetic pen [p] Add anchor tool [+] Delete anchor tool [-] Select tool directly [a] Text, text mask, vertical text, vertical text mask [t] Measurement tool [u] Linear gradient, radial gradient, symmetrical gradient, angle gradient and diamond gradient [G] Paint bucket tool [k] Suction pipe and color sampler [I] Grip tool [h] Scaling tool [z] Default foreground and background colors [D] Switch the foreground and background colors [X] Switch between standard mode and fast mask mode [Q] Standard screen mode, full screen mode with menu bar, full screen mode [F] Temporarily use the moving tool [Ctrl] Temporary use of color absorption tool [Alt] Temporary use of gripper tool [space] Open the tool options panel [Enter] Quickly enter tool options (there is at least one adjustable number in the current tool options panel)  to  Choose brush [ or ] cyclically Select the first brush [shift]+[ Select the last brush [Shift】+【]+] Create a new gradient (in Gradient Editor) [Ctrl]+[N] File operation Create a new graphic file [Ctrl]+[N] or [Ctrl]+double-click in the blank space Use the default settings to create a new file [ctrl]+[alt]+[n] Open the existing image [ctrl]+[o] Open as … [ctrl]+[alt]+[o] Close the current image [ctrl]+[w] Save the current image [ctrl]+[s] Save as … [ctrl]+[shift]+[s] Save copy [ctrl]+[alt]+[s] Page setup [ctrl]+[shift]+[p] Print [ctrl]+[p] Open the preset dialog box [ctrl]+[k] According to the last preset dialog box [alt]+[ctrl]+[k] Set the “general” option (in the preset dialog box) [ctrl]+ Set “save file” (in the preset dialog box) [ctrl]+ Set “display and cursor” (in the preset dialog box) [ctrl]+ Set “transparent area and color gamut” (in the preset dialog box) [ctrl]+ Set “unit and scale” (in the preset dialog box) [ctrl]+ Projection effect (in the Layer Style dialog box) [Ctrl]+ Inner Shadow Effect (in the Layer Style dialog box) [Ctrl]+ External lighting effect (in the Layer Style dialog box) [Ctrl]+ Internal lighting effect (in the Layer Style dialog box) [Ctrl]+ Bevel and relief effects (in the “Effects” dialog box) [Ctrl]+ Glossy effect (in the layer style dialog box) [ctrl]+ Color overlay effect (in the layer style dialog box) [ctrl]+ Gradient overlay effect (in the layer style dialog box) [ctrl]+ Pattern superposition effect (in the layer style dialog box) [ctrl]+ Apply the currently selected effect and make the parameters adjustable (in the Effects dialog box) [A]
Layer blending mode Choose the mixed mode [alt]+[-] or [+] cyclically Normal [ctrl]+[alt]+[n] Threshold (bitmap mode) [ctrl]+[alt]+[l] Dissolve [ctrl]+[alt]+[I] Back [ctrl]+[alt]+[q] Clear [ctrl]+[alt]+[r] The bottom of the positive film stack [Ctrl]+[Alt]+[M] Screen [ctrl]+[alt]+[s] Overlay [ctrl]+[alt]+[o] Soft light [ctrl]+[alt]+[f] Strong light [ctrl]+[alt]+[h] Color thinning [ctrl]+[alt]+[d] Color deepening [ctrl]+[alt]+[b] Dim [ctrl]+[alt]+[k] Turn on [ctrl]+[alt]+[g] Difference [ctrl]+[alt]+[e] Exclude [ctrl]+[alt]+[x] Hue [ctrl]+[alt]+[u] Saturation [ctrl]+[alt]+[t] Color [ctrl]+[alt]+[c] Luminance [ctrl]+[alt]+[y] Color-removing sponge tool+[ctrl]+[alt]+[j] Color sponge tool+[ctrl]+[alt]+[a] Dim dimming/deepening tool+[ctrl]+[alt]+[w] Intermediate dimming/deepening tool+[ctrl]+[alt]+[v] Highlight Dim/Deepen Tool+[Ctrl]+[Alt]+[Z] Select function Select all [ctrl]+[a] Cancel the selection [ctrl]+[d] Select [ctrl]+[shift]+[d] again Feather selection [ctrl]+[alt]+[d] Select [ctrl]+[shift]+[I] in reverse [Enter] of the numeric keyboard with path change selection Load selection [ctrl]+click the thumbnail in the layer, path, channel panel Filter Do the last filter [ctrl]+[f] again according to the last parameter Fade the effect of the last filter [ctrl]+[shift]+[f] Repeat the last filter (adjustable parameter) [Ctrl]+[Alt]+[F] Select the tool (in the 3D variation filter) [v] Cube tool (in the 3D Change filter) [M] Sphere tool (in the 3D Change filter) [n] Column tool (in the 3D change filter) [c] Trackball (in “3D change” filter) [r] Panorama camera tool (in the 3D variation filter) [e] View operation Display color channels [ctrl]+[~] Display monochrome channel [ctrl]+[number] Display composite channel [~] Preview in CMYK mode (switch) [ctrl]+[y] Turn on/off color gamut warning [ctrl]+[shift]+[y] Enlarge the view [Ctrl】+【+ [+] Zoom out view [ctrl]+[-] Display [ctrl]+ on the canvas Actual pixel display [ctrl]+[alt]+ Scroll up one screen [PageUp] Scroll down one screen [PageDown] Scroll one screen to the left [ctrl]+[page up] Scroll one screen to the right [ctrl]+[page down] Scroll up by 10 units [shift]+[page up] Scroll down by 10 units [shift]+[page down] Scroll left by 10 units [shift]+[ctrl]+[page up] Scroll right by 10 units [shift]+[ctrl]+[page down] Move the view to the upper left corner [Home] Move the view to the lower right corner [End] Show/hide the selection area [Ctrl]+[H] Show/hide path [ctrl]+[shift]+[h] Show/hide ruler [Ctrl]+[R] Show/hide the reference line [ctrl]+[; 】 Show/hide grid [ctrl]+[“].
Close to the reference line [ctrl]+[shift]+[; 】 Lock the reference line [ctrl]+[alt]+[; 】 Close to the grid [ctrl]+[shift]+[“] Show/hide brushes panel [F5] Show/Hide Color Panel [F6] Show/hide Layers panel [F7] Show/Hide Information Panel [F8] Show/hide the Actions panel [F9] Show/hide all command panels [TAB] Show or hide all palettes except toolbox [shift]+[tab] Word processing (in the Text Tools dialog box) Left aligned or top aligned [ctrl]+[shift]+[l] Align [ctrl]+[shift]+[c] in the middle Right or bottom alignment [ctrl]+[shift]+[r] Select 1 character [shift]+[←]/[→] from left/right Select 1 line [shift]+[↑]/[↓] from down/up Select all characters [ctrl]+[a] Select the character [Shift] from the insertion point to the mouse click point and press it Move one character left/right [←]/[→] Move 1 line down/up [↑]/[↓] Move one word left/right [ctrl]+[←]/[→] Reduce the text size of the selected text by 2 pixels [ctrl]+[shift]+[<] Increase the text size of the selected text by 2 pixels [ctrl]+[shift]+[>] Reduce the text size of the selected text by 10 pixels [ctrl]+[alt]+[shift]+[<] Increase the text size of the selected text by 10 pixels [ctrl]+[alt]+[shift]+[>] Reduce the line spacing by 2 pixels [alt]+[↓] Increase the line spacing by 2 pixels [alt]+[↑] Reduce the baseline displacement by 2 pixels [shift]+[alt]+[↓] Increase the baseline displacement by 2 pixels [shift]+[alt]+[↑] Reduce kerning or kerning by 20/1000 EMS [ALT]+[←] Increase kerning or kerning by 20/1000 EMS [ALT]+[→] Reduce kerning or kerning by 100/1000 EMS [Ctrl]+[Alt]+[←] Increase kerning or kerning by 100/1000 EMS [Ctrl]+[Alt]+[→] Set “plug-in and scratch pad” (in the preset dialog box) [ctrl]+ Set “memory and image cache” (in the preset dialog box) [ctrl]+ Edit operation Restore/redo previous operation [Ctrl]+[Z] Restore more than two operations [ctrl]+[alt]+[z] Redo more than two operations [ctrl]+[shift]+[z] Cut the selected image or path [Ctrl]+[X] or [F2] Copy the selected image or path [Ctrl]+[C] Merge copy [ctrl]+[shift]+[c] Paste the contents of the clipboard into the current drawing [ctrl]+[v] or [F4] Paste the contents of the clipboard into the selection box [ctrl]+[shift]+[v] Free transformation [ctrl]+[t] Apply free transformation (in free transformation mode) [Enter] Transform from the center or symmetry point (in free transformation mode) [Alt] Limit (in free transformation mode) [Shift] Twisting (in free transformation mode) [Ctrl] Cancel operation (including output, filter, etc.) [Esc] Transform the copied pixel data freely [ctrl]+[shift]+[t] Transform the copied pixel data again and create a copy [ctrl]+[shift]+[alt]+[t] Delete the pattern in the box or the selected path [DEL] Fill the selected area or the whole layer with background color [ctrl]+[backspace] or [ctrl]+[del] Fill the selected area or the whole layer with foreground color [alt]+[backspace] or [alt]+[del] The fill dialog box [shift]+[backspace] pops up Fill in [alt]+[ctrl]+[backspace] from the historical record picture control Adjust the color level [ctrl]+[l] Automatically adjust the color level [ctrl]+[shift]+[l] Open the curve adjustment dialog box [ctrl]+[m] Add a new point on the curve of the selected channel (in the’ curve’ dialog box) and press [Ctrl] in the image Add new points on all curves except the compound curve (in the’ curve’ dialog box) [ctrl]+[shift] Press a little Move the selected point (in the’ curve’ dialog box) [↑]/[↓]/[←]/[→] Move the selected point by 10 points (in the’ curve’ dialog box) [shift]+[arrow] Select multiple control points (in the’ curve’ dialog box) [Shift] and press it Move forward control points (in the “curve” dialog box) [ctrl]+[tab] Move back the control point (in the “curve” dialog box) [ctrl]+[shift]+[tab] Add a new point (in the Curve dialog box) Click the grid Delete points (in the’ curve’ dialog box) [Ctrl] add points and press points Deselect all points on the selected channel (in the’ Curve’ dialog box) [Ctrl]+[D] Make the curve grid finer or coarser (in the’ curve’ dialog box) [Alt] and press the grid Select color channel (in the “curve” dialog box) [ctrl]+[~] Select monochrome channel (in the “curve” dialog box) [ctrl]+[number] Open the “color balance” dialog box [ctrl]+[b] Open the hue/saturation dialog box [ctrl]+[u] Full picture adjustment (in hue/saturation dialog box) [ctrl]+[~] Adjust only red (in the hue/saturation dialog box) [ctrl]+ Adjust only yellow (in the hue/saturation dialog box) [ctrl]+ Adjust only green (in the hue/saturation dialog box) [ctrl]+ Adjust cyan only (in the hue/saturation dialog box) [ctrl]+ Adjust only blue (in the hue/saturation dialog box) [ctrl]+ Adjust magenta only (in the hue/saturation dialog box) [ctrl]+ Color removal [ctrl]+[shift]+[u] Inverse phase [ctrl]+[I]
Layer operations Create a new layer from the dialog box [Ctrl]+[Shift]+[N] Create a new layer with default options [Ctrl]+[Alt]+[Shift]+[N] Create a layer by copying [ctrl]+[j] Create a layer by cutting [Ctrl]+[Shift]+[J] Group with previous layer [ctrl]+[g] Ungroup [ctrl]+[shift]+[g] Merge or merge join layers down [ctrl]+[e] Merge visible layers [ctrl]+[shift]+[e] Seal or seal the connection layer [ctrl]+[alt]+[e] Seal the visible layer [ctrl]+[alt]+[shift]+[e] Move the current layer down one level [Ctrl]+[ Move the current layer up one level [Ctrl】+【]+] Move the current layer to the bottom [Ctrl]+[Shift]+[ Move the current layer to the top [Ctrl]+[Shift]+] Activate the next layer [alt]+[ Activate the previous layer [Alt】+【]+] Activate the bottom layer [shift]+[alt]+[ Activate the top layer [shift]+[alt]+] Adjust the transparency of the current layer (the current tool has no numerical parameters, such as the mobile tool)  to  Keep transparent area of current layer (switch) [/] Projection effect (in the “Effect” dialog box) [Ctrl]+ Inner shadow effect (in the “Effect” dialog box) [Ctrl]+ External luminous effect (in the “Effect” dialog box) [Ctrl]+ Inner luminous effect (in the “Effect” dialog box) [Ctrl]+ Bevel and relief effects (in the “Effects” dialog box) [Ctrl]+ Apply the currently selected effect and make the parameters adjustable (in the Effects dialog box) [A]
Second, InDesign software InDesign software is a design software located in the field of professional typesetting, and it is a new platform for the company’s professional publishing scheme. Issued by Adobe company on September 1, 1999. It is based on a new open object-oriented system, which can achieve high scalability. It also establishes a core that third-party developers and system integrators can provide customized magazine, advertising design, catalog, retailer design studio and newspaper publishing solutions. Plug-in functions can be supported.
For ordinary users, the most widely used typesetting software in the field of prepress design is Adobe’s PageMaker, but this does not mean that PageMaker is the best. QuarkXPress of Quark Company (which is used in most countries and regions in Europe and America) and FIT of FOUNDER of Peking University are superior to PageMaker in professional performance, but these two softwares are not widely used due to various factors. For example, Quark has not been focusing on China, so the simplified Chinese MAC version is slow to upgrade, and the PC version is rare; And Founder FIT mainly cooperates with other software developed by Founder Group of Peking University to specialize in large-scale objects with coherence and systematicness, such as newspapers and publishing houses. In addition, the back-end phototypesetting output of FIT also has limitations, that is, the PS files of FIT can only be output on expensive Founder RIP, etc., so ordinary users have to use PageMaker, which has fast upgrade and convenient output, but its functions can not satisfy professionals. PageMaker was originally inherited from Aldus by Adobe, and its core technology is relatively old, with many shortcomings. It is obviously impossible for PageMaker to beat QuarkXPress to occupy a place in the field of prepress design for a long time. Therefore, Adobe released a typesetting software with more powerful functions on September 1, 1999. This innovative typesetting software is InDesign, which has been countered by Quark Company in the field of typesetting in the past 10 years and fully realized the leading position of its desktop publishing system.
It is usually divided into four steps: creating a layout; Typesetting; Adjustment and modification; Output.
First, create a layout:
1 file menu-new-document.
2 Set in the dialog box that appears: first decide the basic page number. Select “Main Text Box” to facilitate the unification of text boxes in the future. Determine the page size and binding direction. Then determine the bleeding value. Select the printable area value if necessary. Select “Margins and Columns” when finished.
Note: if you want to open InDesign repeatedly in the future, the document will automatically show the parameters you want as the default parameter settings, then you need to:
A. select menu: layout-margins and columns, and set corresponding parameters.
B select menu: file-document setting, and set corresponding parameters.
When these tasks are completed, whenever you open a new document, the program will take these parameters as the default values of the new document.
3 In the subsequent dialog box, select the edition center size, number of columns, text layout and column spacing, etc. Choose “good”.
4 is the master page. Select the Pages toolbox. Select the corresponding master page.
Select menu: layout-automatic page coding.
Set the page number position, font and other related parameters on the master version.
1) insert text:
Method 1: Select “Text Tool” in the toolbar. Press and hold the “Apple+＋Shift” key, and click the edition center with the mouse, so that the main text box is applied to the current layout.
Choose menu: file-place.
Select the desired text and select Show Input Options in the lower left corner of the dialog box. In the subsequent dialog box, after setting the required parameters, click OK. Place the desired text into the. (you can select “automatic document layout” as required).
Method 2: Open the required text file, “select all”, “copy”, click the Indesign page, and “paste”.
Method 3: select the required text and drag it onto the Indesign page.
2) Define character style and paragraph style: Select the “Paragraph Style” toolbox. In the dialog box that appears. Select various items in turn and set them. It should be noted that in the “Overall” item, you can set your own shortcut keys to improve work efficiency.
3) Text editing: select menu: Edit-Text Editor.
Put the defined paragraph styles into the required paragraphs.
4) Place graphics: select the “Outline” tool in the tool frame. Draw a graphic box with corresponding size at the position where the graphic needs to be placed.
Choose menu: file-place.
Select the desired graphic placement.
5) Graphic typesetting: select menu: Window-Text and Table-Text Wrapping.
Choose how to wrap text according to your needs.
III. Adjustment and revision:
1) Text adjustment: it involves global modification and should be adjusted in paragraph style. Modification of local text, adjustment in character style. Now, we need to change the subheadings in the paragraphs to “medium line”. Step: Select the Text Style toolbox. Change the style name to “Text Title”, select “Medium Line Style” in “Font Set”, click “OK” to select text subtitle respectively, and click “Text Title” in character style.
2) Paragraph style adjustment: adjust and modify the originally defined paragraph style according to the overall layout. Select paragraph style toolbox select indent and spacing type 7MM in first line indent. Click “OK”. At this point, the paragraph is automatically indented before it.
3) Graphic adjustment:
Select the graphic to be modified. Choose menu: items.
Select Shadow, Feather, Gradient, Corner Effect, etc. as needed.
When adjusting graphics, you need to adjust the aspect ratio of graphics content, and use the Direct Selection Tool in the toolbar.
4) Layout order adjustment: Open the “Page” toolbox. At this time, you can see thumbnails and page numbers of all pages. Drag and drop the mouse to put the page to be adjusted before or after.
Fourth, prepress preparation:
1) check information: select menu: file-prepress preparation.
In the dialog box that appears, give a detailed report of everything you have done. Producers and operators who export films should carefully read and check this report. Key points should be checked:
A. page size, bleeding and typesetting direction; B. Picture type and link status; C. color attributes and spot colors; D. Check font types and attributes; E. external plug-in.
2) Modification: After the inspection is completed, the contents and settings that do not meet the requirements are returned to the original file for modification.
3) Packaging: select menu: File-Packaging In the dialog box that appears, fill it out item by item as far as possible as required. Click “OK” after filling it out.
At this time, a new dialog box appears. According to your needs, pay attention to selecting various contents in the command box in the lower left corner, and click OK.
At this time, Indesign will automatically create a new folder, and make a complete backup of all the relevant texts, graphics and various files in this work. It is convenient for you to classify and save, and can be provided to the output center. It avoids the defect of missing documents which often appeared in the past.
4) After being sent to the output center, the output operator should also repeat the above work and make corresponding parameter settings according to the output requirements.
Iii. operation principle and application of phototypesetter:
1. use environment 1) keep the use environment clean and keep the external surface of the equipment clean 2) Regularly clean the cots (cots passing through the film and cots in the film box) 3) Please do not put heavy objects, water cups, etc. on the phototypesetter, and please do not lean on it; 4) Be grounded safely. Do not open the cover when the phototypesetter drum rotates. After the drum stops rotating, turn off the power supply and check again.
2. Requirements for using film:
Used film: small shaft with inner diameter of 50.8mm, medicine film facing outward, soft flange, 60m reel film with width of 457mm (four startup) and 660mm (opposite startup), and red laser with wavelength of about 633nm.
Film brands: imported films such as Konica and Aierfa, domestic films such as Huaguang and Le Kai 3. Pay attention to the setting accuracy and size of RIP should be consistent with the setting accuracy and size of phototypesetter; If the files interpreted by RIP use 2400dpi and four-opening, the phototypesetter should also be set to four-opening, and 2400dpi can be used for typesetting; 4. How to adjust the relationship between film density and film punching time, liquid medicine concentration and light intensity 1) if the sheet density is too high, reduce the sheet punching time; Or reduce the light intensity value 2) If the film density is too small: increase the film punching time or increase the concentration of liquid medicine; Or increase the light intensity value Note: Generally, increase or decrease time is used to adjust density, and less light intensity is used to adjust density.
5. Linearization test and adjustment Linearization adjustment can only be made on the basis of adjusting the density to 4.0-4.2. If there is no densitometer, the following settings are for reference only 100％ 100 98％ 98 95％ 95 90％ 91 85％ 86 80％ 81 75％ 76 70％ 72 65％ 67 60％62 55％ 58 50％ 54 45％ 48 40％ 43 35％ 38 30％ 32 25％ 27 20％ 22 15％ 16 10％ 11 5％ 6 3％ 4 1％ 2 IV. Punching Machine 1, the use of liquid medicine requirements Use liquid medicine, and refer to the description of the liquid medicine used for specific proportion; Note: different brands of potions can not be mixed with each other, and fixative and developer potions can not be mixed with each other; Liquid medicine replacement cycle: change the liquid medicine in 7-15 days, and thoroughly clean the medicine tank and shaft bracket; Or depending on the film quality. Water replacement cycle: completely replace water in 1-2 days; 2. Maintenance schedule Use a cleaning bottle to rinse the gear liquid on the liquid medicine.
Check whether the gears and cards on the roller assembly are intact in 7 days.
10 days to clean the filter element of liquid medicine, remove the crystal at the edge of the liquid tank, and clean the replenishment pump and one-way valve.
15 days total drive shaft worm gear, chain oil.
After 30 days, discharge the liquid medicine, clean the liquid tank once, clean the roller assembly, and refuel with the fan.
3. Cleaning method 1) For daily cleaning, just use a cleaning bottle prepared at random, fill it with clear water, aim the nozzle at the roller and gear above the liquid level, and spray some clear water slightly. It doesn’t matter if the clear water drops into the liquid tank.
2) Cleaning the drug filter: Take out the drug filter every ten days, soak it in warm water for about half an hour, and then rinse it off with clear water. Never clean the developing and fixing filter in the same container.
3) Clean the supplementary pumps. To avoid assembly errors, it is best to clean them one by one. Loosen the screw sleeve at the inlet or outlet, take out the one-way valve, soak it in clear water, gently pull out the cone of the one-way valve, clean the dirt on all sides of the cone, and then restore it. Make-up pump inlet and outlet are provided with one-way valves with directionality, so be sure not to make mistakes in direction.
4), medicine tank cleaning, first set on the corresponding drain valve plastic pipe (pay attention to developing and fixing don’t share a pipe), put the liquid into the corresponding medicine barrels, residue into the sewer, and then put water in the liquid tank, clean with a soft brush or cloth.
4. Let’s focus on the detailed overhaul and maintenance process Laser phototypesetter is one of the main equipments in prepress system at present. Therefore, it is important to pay special attention to maintenance, especially to repair the equipment in idle time, which is an important link to ensure the normal operation of laser phototypesetter, ensure the product quality, and find out the signs of accidents in time and solve them. Personally, maintenance should be carried out from the following aspects:
1. The surface of the laser phototypesetter should be thoroughly cleaned and wiped, and the machine should be clean and sanitary. Data lines and cables shall be kept neat, without any discount or knot. Relevant tools shall be placed neatly, and there shall be no items unrelated to production around the laser phototypesetter.
2. The laser system is an important part to ensure the film quality, and the normal operation of the laser system is an important link to ensure that the recording accuracy and density meet the standard. It can be overhauled from three aspects: ① protective cover, ② vacuum pump and ③ laser scanning head. First, check whether the protective cover is damaged, displaced or loose; Secondly, check whether the dust filter paper cup of the vacuum pump is blocked by sundries, judge whether there is dust adsorption on the laser scanning head according to the film density, and timely adjust and repair if problems are found, so as to avoid accidents and ensure the normal operation of the laser phototypesetter.
3. The bridge is the “intermediate bridge” to ensure that the film is accurately transmitted to the processor after exposure. For its maintenance, it is mainly to check the vulnerable parts, such as spring elasticity, sensor sensitivity, screw looseness, and all accessories are in good condition. If problems are found, repair them in time to avoid failure.
4. Cleaning of the washing machine. Remove the top cover, drying cover and condensing cover, and scrub the rollers, cross guide parts and film input table with wet cloth; Check whether the supplementary liquid container is well sealed and empty the waste liquid container; Empty the water washing tank, check whether the air vent is blocked and the air exhaust duct is unobstructed, and close the water inlet and outlet valves. Repair problems in time to ensure the normal operation of equipment.
5. The developing and fixing parts are indispensable parts to ensure the film quality, which directly affects the printed matter quality. During maintenance, the developing (fixing) bracket should be carefully cleaned to ensure that there is no crystalline substance on the film guiding part; Under the condition of long-term shutdown, if conditions permit, all the liquid medicine in the developing and fixing tank can be discharged and stored in a sealed container to prevent oxidation. Empty the developing (fixing) tank to ensure that the tank is clean, sanitary and free of sundries.
6. Lubrication of laser phototypesetter. The function of lubricating oil is to reduce the friction between parts and prevent them from rusting. The special lubricating oil (water-based) distributed with the machine should be used as the lubricating oil of the flushing machine, and the bridge guide rail can be lubricated with paste lubricating oil (such as butter). Lubrication of the flushing machine can prolong the service life of the machine and enable the machine to run smoothly.
Paying attention to the daily maintenance of phototypesetter can not only ensure the consistent output quality of phototypesetter. But also can prolong the service life. Ordinary maintenance needs to do the following: (some supplements to the maintenance written at the beginning) 1, keep the room clean, especially don’t have more dust; 2. Keep the low temperature environment. Do not exceed 22 degrees Celsius in summer. Because most imagesetters have long continuous working hours. Heat storage is large. Is not conducive to heat dissipation of electrical components. Affect the service life of electrical parts; 3. The power supply system of phototypesetter shall be reliably grounded. Avoid current breakdown of components; 4. Wipe the cots in the phototypesetter with a cloth dipped in clear water every time the film is replaced, so as to ensure that the cots have normal elasticity and avoid wiping with chemicals such as alcohol.
5. Under the condition of keeping the room clean, ask professional engineers to clean the optical path every six months. On the one hand, it can keep the output quality better, on the other hand, it can prolong the service life of the laser tube; 6. The exposure value of phototypesetter should not be set too high. Because too high will affect the dot curve and shorten the service life; 7, phototypesetter had better not stop for 24 hours. Proper rest is not only good for machines. It is also good for people.
Calibration of phototypesetter is one of the most important steps in making high-quality images.
It is difficult to obtain high-quality dot by using uncalibrated imagesetter, and it is not difficult to calibrate imagesetter as long as there are proper tools. In this way, if you want 20% outlets, the result should be 20%, not 16% or 23%. In addition to accurate hierarchical replication, correct alignment of the phototypesetter can also help you avoid the disconnection of the highlights and the merging of the dark tones.
We also have a set of quality inspection standards for the film sent out. Here’s to focus on the precautions for the film:
In fact, the output of film is an exposure process similar to photography. Firstly, the graphics and texts are processed by RIP into dot matrix images (that is, graphics and texts composed of dots), which are then converted into signals that dominate the laser. By using the longitudinal and transverse movement of the laser relative to the film, the laser dots (that is, dots) are hit (shot) at the corresponding positions of the film to expose the corresponding parts of the film, and then the unexposed parts are washed through the developing and fixing process of the developing machine As for the quality standard of film, I think it should mainly include the following four aspects:
1. Field density and fog, which are the basis for measuring the quality of film. Fog refers to the absolute density of blank film, that is, the density of blank film measured after the densitometer is absolutely cleared (null clearing). The film with fog value < =0.03 is excellent, and it is qualified between 0.03 and 0.07. The so-called field density refers to the density value of large field blocks. Due to the small area of the gray ladder ruler in the general distribution software and the trachoma in some film films, the measured value of the field density is smaller than the actual value, which is generally qualified when it is between 3.5 and 3.8. However, if there is a large field, it must be ensured that its density value is between 4.0 and 4.3 to ensure the color saturation of the printed matter without merging the dark tone levels.
2. Linearization value, which is the main factor to measure the quality of film. Generally, it should be ensured that the difference between the marked value on the film gray ladder ruler and the measured value < = 2 is qualified. However, because the general high-precision printing press has a certain degree of color adjustability, we can guarantee the quality of printed matter as long as the linearization difference is less than = 5.
Third, the shape of the mesh point, the angle of the mesh point and the number of hanging mesh lines, the mesh point should be smooth, solid, no sawtooth and no tail; The net angle meets the standard (generally monochrome 45 degrees, the difference between four colors is 30 degrees) and does not hit the net; The number of screen wires is suitable for printing media (e.g., newsprint is not higher than 120LPI, coated paper is not lower than 133LPI).
Fourth, the film quality after exposure is the last pass, and it is also the most easily overlooked factor. There is no trachoma on the film, no scratch on the film, no oil trace, and no “white spot” that has not been removed by fixing. It can be said that it is a film with good quality.
Some experiences on quality management of laser phototypesetting First, check the quality of the manuscript From the point of view of total quality management, the quality of phototypesetting should be controlled from the original manuscript. Because the quality of original manuscript determines the quality of photo-typesetting. Therefore, the original must be carefully examined. Check whether there are scratches and dirt on the surface of the manuscript, whether the text and lines are complete, whether there are any broken pens, etc. Second, see if the picture is color cast. Under natural light or standard light source close to daylight color, observe whether there is interference of other colors in the achromatic parts such as white, gray and black on the reflection manuscript; Third, see if the main colors are accurate. Generally speaking, the color of reflected manuscripts (such as photos, etc.) is slightly exaggerated than the color of the actual scenery, that is, it is brighter than the original color. For example, the reflection draft with characters as the main body should be based on the ruddy complexion of the face; Fourth, see if the contrast is moderate. Contrast of reflected manuscript includes brightness difference, color contrast and contrast balance. The brightness difference is moderate, and there are rich transitional color levels between the high-tone part and the dark-tone part; If the color contrast is moderate, the color concentration of the reflected manuscript will be large and it will have a strong three-dimensional sense. If the contrast balance is good, the color performance of the same color in the high-tone part and the dark-tone part will be very consistent.
Second, the quality inspection of prepress output documents The inspection items that need to be carried out on the documents to be output by phototypesetting mainly include:
1. Check whether the registration line, color code and various printing and cutting lines are complete. The registration line should be black with four colors (i.e., c = 100%, m = 100%, y = 100%, k = 100%), and there is no registration line, so the output four-color or multi-color photo-typesetting film is equal to a pile of waste products.
2. Check the image color mode.
When the laser phototypesetter outputs color separations, the color mode of all color images should be CMYK mode. Therefore, it is necessary to carefully check whether the color mode of the linked images is correct through the linked image table before output. If the image is still in RGB or Lab mode, the color mode should be converted in the image processing software, otherwise, only the black version will have the image when outputting the color separation, or the color separation is not ideal, or even can not be output; For black and white pictures, the image mode should be grayscale or binary mode, and only the black version has dot information when outputting.
3. Check whether the resolution of the pictures used meets the printing requirements.
Ensure that scanned images, photographs and other dot matrix pictures have proper resolution, which is necessary to ensure the quality of output photo-typesetting (the resolution has nothing to do with PostScript vector diagram, and they will be printed with the maximum resolution of the output device). The following lists the resolution setting standards of some common different publications:
The newspaper uses a scan resolution of 125-170dpi, and the resolution of printed matter images is set to 1.5 to 2 times that of the screen line (lpi) (2 times will make it more flexible to enlarge images). 85 ~ 133lpi for newspaper printing.
Periodicals, magazines and publicity materials use scan resolution of 300dpi, because magazines generally use 133 or 150lpi for printing.
The scan resolution of high-quality books is 350 ~ 400 dpi, because most beautifully printed books are printed with 1750 ~ 200 lpi. What needs to be explained here is that it is best not to use the pictures downloaded from the Internet. The resolution of these pictures is generally only 72dpi, and some of them are lower. No matter how they are processed, the output effect will not be very good.
4. Explain the preview release results through RIP. RIP interpretation preview is consistent with the final release result. Through preview, check whether the image linked to the file is correct, whether the image interpretation is in good condition (if the copy is broken, RIP interpretation will make mistakes), whether the image color is consistent with the original, whether the text is garbled, whether the elements of the file are misplaced, whether the black version is overprinted, etc. This is the final inspection before output, so be careful to avoid quality problems.
Third, check the operation of phototypesetter After the phototypesetter is started, its working status can generally be seen in the graphical interface of the control software of the output workstation, and the items to be checked mainly include:
1. Whether the setting of laser phototypesetter matches with the system equipment and works normally. In order to ensure the stability of laser quantity, the laser head should be tested and calibrated regularly.
2. Whether the concentration and temperature of the liquid medicine of the punching machine are normal. According to the performance of phototypesetting film and liquid medicine, set the parameter values of development and fixation, test them regularly with test strip and ladder ruler, and do a good job in daily cleaning and maintenance of the film punching equipment to prevent the phototypesetting film from being dirty due to turbidity.
3. Whether the performance of phototypesetting film and liquid medicine itself is stable. In order to ensure the stability of phototypesetting quality, variable factors should be reduced as far as possible in the use of raw materials, so that the use of raw materials is relatively fixed.
4. Photographic film is easily scratched due to the influence of foreign bodies in the process of equipment operation and transmission, so the transmission parts should be cleaned and wiped regularly, and the parts should be replaced in time when damage is found.
Four, the quality inspection of the output phototypesetting film After output, it is necessary to check the output phototypesetting film. As the last process before printing, phototypesetting film inspection should really play the role of addendum plugging, and it should be given enough attention. Check the contents are:
1. Check the accuracy of fitting. Generally speaking, the registration error of continuously output four-color or multi-color phototypesetting films is very small. If a living part needs one or two-color supplementary plates, and phototypesetting films of other colors are output one day, two days or more ago, the registration accuracy of various phototypesetting films should be carefully checked. If the registration error is very large, phototypesetting films of all colors should be continuously output. Of course, this should be determined according to the service time and working stability of phototypesetters. Some phototypesetters have great registration errors for the continuous output of four-color phototypesetters, so it should be considered to repair or update the machines.
2. Check the impression relationship of various color plates against the original manuscript or proofs. Sometimes, due to personnel operation or machine failure, the layout elements will be lost and misplaced. For books and periodicals publications, the best inspection method is to attach the photo-typesetting film to the original manuscript or proofs. If there are any errors or omissions, they can be clearly seen. Of course, in this process, we should pay attention to avoid scratching the film and affecting the printing quality.
3. Check whether the phototypesetting film is dirty. Dirty phototypesetting is a common problem in the output process. Generally speaking, the water washing tank should be cleaned before starting up every day, and the water purification equipment with external water supply switch should be turned on before water injection, so as to avoid the sediment deposited in the pipeline being brought into the water washing tank, scratching or sticking to the film, which will affect the quality of phototypesetting film; After the work, the water washing tank should be emptied and carefully cleaned, otherwise impurities may be produced in the water, causing the washing quality to decrease.
4. Check the screen angle of various phototypesetting films. In order to avoid hitting the net, in theory, the difference between the four colors should be 22.5 degrees. In practice, the four colors are printed at 15 degrees, 45 degrees, 75 degrees and 90 degrees. Among them, the yellow version has weak visual stimulation and poor visual perception, so it is generally set at 90 degrees. Because people’s vision is most sensitive to 45 degrees, the main color of the manuscript is generally set at 45 degrees. The specific setting shall be carried out according to the printing design. The net angle can be checked by a magnifying glass or measured by a net angle measuring tool. In addition to the special requirements of customers, the setting of general net angle should not be changed at will to avoid unnecessary losses.
5. Check the field density of the control slice. The density of phototypesetting film can be checked by transmission densitometer. Generally, the density value can be above 3.5, but it is better to be around 4.2. The density is too high, which will lead to printing paste phenomenon and low density. For products with text and field layout, the printed matter is light in ink color and looks untrue. At this time, it is necessary to replace the fixing solution or clean the laser head to ensure the stability of phototypesetting quality.
To sum up, serious and accurate inspection and corresponding measures to control the quality of phototypesetting film can not only improve the quality of phototypesetting film, but also improve the production efficiency.
Let’s briefly talk about outlets:
At present, the outlets we use are relatively fixed, just for understanding. Network cable is the number of screening lines. The expression unit is lpi, and 75~90 lines (75~90 lpi) can be used for general reporting lines. 150~175 lines (150~175 lpi) for color offset printing. Because the former dot has a linear shape, it is customary to call all dot density network lines. To be precise, it is the precision (resolution) of laser phototypesetter interpreting digital files on film. The so-called network line is the definition of printing, and what we design is the resolution to express the definition of images. The relationship between network cable and resolution is: 1.5 times of network cable is equivalent to resolution (generally speaking). In the printing process, the continuous harmonic halftone image is adjusted by the dot density. By mixing the dots of CMYK four colors, you can show an infinite number of colors.
At present, there are two different types of dots used in printing process: AM dot and FM dot.
Amplitude modulation dot Amplitude modulation dot is the most widely used dot at present. Its dot density is fixed. By adjusting the size of dot, it shows the depth of color, thus realizing the transition of hue. In printing, the use of amplitude modulation dot mainly needs to consider dot size, dot shape, dot angle, screen precision and other factors.
Dot size The dot size is determined by the dot coverage rate, which is also called inking rate. Generally, it is customary to use “success” as the measurement unit. For example, outlets with 10% coverage rate are called “10% outlets”, outlets with 20% coverage rate are called “20% outlets”. In addition, outlets with 0% coverage rate are called “off-line”, and outlets with 100% coverage rate are called “field”.
The tone of printed matter is generally divided into three levels: light tone, middle tone and dark tone. The network coverage rate of the bright part is about 10% ~ 30%; The network coverage rate of the intermediate adjustment part is about 40% ~ 60%; The dark part is 70% ~ 90%. The isolated network and the field part are divided separately.
Dot shape The dot shape in printing is not just a single round shape in everyone’s imagination, but can be divided into three types: square, round and diamond.
Square outlets are checkerboard under 50% coverage. Its particles are sharp, and it has a strong ability to express levels. Suitable for lines, graphics and some hard-tone images.
Circular mesh points are independent whether they are in bright tone or middle tone, and only partially connected when they are in dark tone. Therefore, for the poor performance of the mining level, it is seldom used in four-color printing.
Diamond dot combines the hard of square dot with the soft of round dot, and has natural color transition, which is suitable for general images and photos.
Dot angle In printing plate making, the choice of dot angle plays a vital role. If you choose the wrong dot angle, interference fringes will appear.
Common dot angles are 90 degrees, 15 degrees, 45 degrees and 75 degrees. 45-degree outlets perform best, stable and not dull; The angle stability of 15 degrees and 75 degrees is worse, but the visual effect is not rigid; The angle of 90 degrees is the most stable, but the visual effect is too dull and has no aesthetic feeling.
When two or more kinds of mesh points are nested together, there will be mutual interference. When the interference is so serious that it affects the beauty of the image, it will appear as “turtle print”.
Generally speaking, when the angle difference between the two kinds of mesh points is 30 degrees and 60 degrees, the whole interference fringe is still beautiful; Secondly, the dot angle difference of 45 degrees; When the angle difference between the two kinds of dots is 15 degrees and 75 degrees, the interference fringes will damage the beauty of the image.
Number of dot lines The size of the screen number determines the fineness of the image, similar to the resolution. Common applications of the screen number are as follows:
Line 10-120: low-quality printing, posters, posters and other printed materials with relatively large areas for long-distance viewing, are generally printed with newsprint and offset paper, and sometimes with low-gram sub-art paper and coated paper.
150 lines: this precision is generally used in common four-color printing, and is available on all kinds of paper.
Line 175-200: Exquisite picture books, pictorial books, etc., most of which are printed with coated paper Line 250-300: Most of the albums with the highest requirements are printed with high-grade coated paper and special paper.
The following are the picture effects of several different lines (the effect on the screen is really unsatisfactory, only for reference) Frequency modulation network Screen adjustment network is a new screening method developed since 1990s, which is different from amplitude modulation network in that the size of screen adjustment network is fixed, and it realizes gradation by controlling the density of network. The dots in the bright part are sparse, while those in the dark part are dense.
How many dot points are seen from the net mirror.
Net-forming: just put down three outlets of the same size between two diagonal outlets.
Two-in-one net: just put two net points of the same size between two opposite net points.
30% net: just put 1.5 net points of the same size between two opposite net points.
40% net: just put 1.25 outlets of the same size between two diagonal outlets.
50% net: just put one net point of the same size between two opposite net points.
10% net corresponds to 90% net. 20% net corresponds to 80% net. 30% net corresponds to 70% net. 40% net corresponds to 60% net. Only the size of outlets is just the opposite of the distance between them.
(a 300-resolution bitmap, which we know is an image composed of 300 square pixels per inch. When the figure is enlarged, it will be found that it is composed of countless dots of different sizes. Because the printed matter is composed of dots, the number of screen lines of printed image refers to the number of screen lines per inch of printed matter in the horizontal or vertical direction, that is, the number of screen lines. It is called the number of screen lines because the earliest print outlets are linear. The unit of the number of hanging net lines is Line/Inch, or LPI for short. For example, 150Lpi means adding 150 net wires per inch. Screen images. The larger the number of nets, the more the number of nets, the denser the outlets, and the richer the hierarchical expressive force. The bigger the dot, the darker the color and the darker the level; The smaller the dot, the lighter the color and the brighter the level. The line accuracy (Lpi) does not correspond to the resolution (DPI) of 1: 1. For example, a picture with 150 lines requires a resolution of about 300Dpi. The resolution is about twice the number of lines. If you don’t pay attention to theory. It can be understood as the density of film or ink! ) Intermittent color: Mixed colors prepared by mixing two primary colors are called intermediate colors or secondary colors, such as R, G, B, M80%, Y70%, C20%, Y80%, etc. Intermediate color is also called secondary color Multicolor: The color produced by the mixture of primary and intermediate colors, or the mixture of two intermediate colors, is called multicolour or tertiary color. In fact, multicolor is a mixture of three primary colors, which is only a combination of one primary color.
Complementary color: when two kinds of pigments are mixed, they are black, so the two colors are complementary, and the intermediate color formed by mixing any one of the three primary colors with the other two primary colors is called complementary color. E.g. m and g are complementary colors. If the two colors are mixed to form white, they complement each other.
What is the trap value determined by? What is the difference between Choke and Spread? What’s the meaning of Keep away?
(1) Trapping control is carried out at the interface where two colors meet, and the process of shrinking or expanding the foreground (or background), hollowing out or leaving empty is called trapping value. In order to avoid white exposure at the lap joint, the trapping value should be slightly higher than the four-color registration accuracy of the printing press. Due to the different printing processes and the different precision of paper and printing machinery, the more precise the printed matter, the higher the registration precision and the lower the trapping value. Typical trapping values have been published by the U.S. Printing Service and printing plants. For example, sheet-fed offset printing uses coated paper with a dot line number of 150lpi and a trapping value of 0.08mm；; For offset printing of newsprint web, the number of screening lines is 100lpi, and its trapping value is 0.15 mm.
(2) Shrinkage is to increase the area of the (light-colored) background, so that it intrudes into the darker foreground (text or picture) at the boundary, while keeping the outline shape of the foreground unchanged.
Expansion is to increase the foreground area with lighter color, and make it invade the background area with darker color at the boundary, while keeping the background contour shape unchanged.
(3) When the background is black and the foreground is hollowed out, the CMY three color plates need to be emptied, so that the foreground outline is defined by the monochrome black plate.
Let’s talk about the main tool of inspection: densitometer Generally, we use a transmission-type black-and-white densitometer, which has a series of advantages such as accurate reading, good stability and convenient operation.
① Clear button ② Display screen ③ measuring platform ④ measuring arm ⑤ power switch ⑥ observation lamp switch Graphic diagram of black and white transmission densitometer Usage:
First, measure the density value:
1. After the densitometer is powered on, press the power switch ⑤ at the lower right, and the display ② will display the “-“mark. The instrument should be preheated for 3 ~ 5 minutes.
2. Without placing any sample, press the measuring arm ④, and the display screen will display “E.1”. Continue to press and hold the measuring arm, and at the same time press the “ZERO” button ① at the upper right of the instrument, and the display shows “0.00”. Release the measuring arm, and the instrument has entered the measuring stage.
3. Align the sample to be tested with the light hole, press down the measuring arm, and the measured density value will be displayed on the display screen.
Second, measure the density difference:
1. The adjustment of the instrument is the same as the steps 1 and 2 of measuring density value.
2. Select any reference value of density D1, and press down the display screen of measuring arm to display D1 density. While pressing the measuring arm, press the ZEPO button to adjust the density D1 to “0.00”.
3. When measuring another density D2, the display shows the difference between the two densities △ d = D2-D1, and when a negative sign appears, it means D2 < D1.
4. When restoring the measured density value, hold down the measuring arm without putting the sample, and press the ZERO button to display “0.00”, that is, it has been restored to the state of measuring density value.
Third, measure the percentage of outlets:
(1) firstly, measure the density (i.e., background density) at the non-dot position of the tested negative film; (2) Release the measuring arm (the displayed value remains unchanged); (3) Press the reset key to display “0.00” (decimal point is cleared), that is, the percentage of outlets is zero; (4) Measure other parts of the film, and the display value should be “000 ~ 100”; (5) If you press the reset key while pressing the measuring arm, the instrument will change to continuous density measurement, and “0.00” will be displayed.
Fourth, observe the sample:
Turn on the switch ⑥ at the lower left of the instrument, and turn on the tricolor fluorescent lamp inside the instrument to observe the tested sample.
This is a gray ladder ruler, which is mainly used for the inspection of projection densitometer. Each piece of gray scale and color scale must have enough area for measurement. It is recommended to use color blocks with height or radius greater than 9mm. Gray blocks do not need to be continuous, and can be designed and arranged according to the width of paper. Attention must be paid to the following points when using the gray scale: in the process of film production, the output dot area ratio must be consistent with the dot area ratio specified on the gray scale, and the transmission densitometer should be used to check that the width of the gray block is at least the same as or larger than the width of the sampling aperture of the reflection or transmission densitometer, so as to obtain the correct measured value. The densitometer must be calibrated every day. The density range of the gray scale should cover the density variation range of the printing press used. When calibrating the gray scale on the printing press, samples should be taken at the point corresponding to the same position of the printing plate and the gray scale, so as to reduce the influence of the difference in printing pressure on the density value. Grey ladder ruler is a useful tool, and if it is used correctly, your color reproduction effect and tone consistency will be better controlled.