Analysis on the quality control of prepress plate making and its influence on printing
1. Introduction There are many factors that affect the quality of printed matter, but if there are problems in the process of prepress plate making, it is impossible to produce qualified printed matter even if the printing materials used are good, the quality of the printing press is high and the binding is exquisite. Pre-press plate making is the prerequisite for producing qualified printed matter. If there is a problem in the process of prepress plate making, it may cause great trouble or even irreparable loss to the post-process.
Because the process of prepress plate making is very complex, there are many factors that affect the quality of final printed matter. The author will discuss the quality control of several important processes and how they will affect the quality of printed matter.
2. Quality control of image scanning The basic job of printing is to copy colors, which are often expressed by pictures. Image scanning is to convert the color information on a picture into storable and editable digital signals through scanning equipment, and then process these digital signals through application software such as image processing software and typesetting software. Therefore, whether the image can be copied accurately and with high quality, that is to say, the information such as gradation, level, contrast and saturation on the original is the basic standard to measure the image scanning quality. Printed manuscript can be divided into reflection manuscript and transmission manuscript. Among them, reflected manuscripts are divided into photos, printed materials, hand-painted manuscripts and printed manuscripts, etc. Transmission manuscript is divided into positive film and negative film. Since each type of manuscript has its own different characteristics, the characteristics of each manuscript should be fully considered when scanning and calibrating.
Evaluation of image scanning quality; (1) set the standard Accurate calibration of the original is the basis of restoring the original, because it is related to the contrast of the whole image and the loss of highlights and dark tones. For example, for a transmission manuscript, if the contrast of the manuscript is normal, the white field should be selected at the density d: 0.35-0.50; If the original is thin, it is necessary to increase the amount of color, and the white field should generally be selected at the density d: 0.20-0.35; If the manuscript is boring and needs to be made brighter, the white field should generally be selected at the density d: 0.60-0.80. (2) Complete gradation and high definition Tone is the hierarchical structure of the whole picture. Complete gradation can make the picture complete, because it is easy to lose the layers in the darkest and brightest places, especially at the edge of a large area of light white picture. If the tone is the body of image color reproduction, then the clarity of image can be said to be the soul of image reproduction. Clarity can concentrate vision: whether an image is clear or not is the most important factor that can attract attention.
(3) Faithful manuscript and higher than manuscript So much for my sharing this time.