Detailed Prepress Operation--Quality Inspection of Electronic Color Sheets

Quality inspection and trimming of the third electronic color separation sheet

Due to the perfection of the color image copying function, the color separation picture produced by the electronic color separation machine can make the color separation picture reach the degree of close to accurate reproduction. However, in the actual operation, due to the operator's level, the defects and insufficiency of the manuscript, and the change of the image reproduction requirements, after the completion of the scanning and color separation, the quality and parameters of the color separation film must also be inspected and some of the parts must be repaired. To meet the requirements of post-process and image reproduction quality.

First, electronic color film quality inspection

The quality inspection of the electronic color separation film refers to the quality of the electronic color separation image and the identification and existence of the electronic color separation image according to the manuscript, process design parameters, user requirements and art processing requirements after the electronic color separation processing of the image is completed. Defective position content, etc., give correction instructions.

1. Image color separation appearance parameter check

The appearance parameters of the image color separation check include the following contents.

(1) Image Finished Product Size: The image finished product size is the sum of the image finished product size and the spelling finish size on the negative chart dichroic sheet. On the Yang picture is the finished product size. Inspection should be performed in both vertical and horizontal directions with an accuracy of 0.01mm.

(2) Scanning control parameters: It includes the number of screen lines, dot shapes, dot angles, image positive/negative, image yin/yang, color logo, production time, crosshairs, etc.

(3) The spelling parameters: whether the image cut is appropriate, whether the fitting is accurate, and whether the density meets the requirement.

(4) Appearance quality: It includes whether the image color separation sheet is smooth, smooth and clean, with or without creases, ripples, and crystal spots.

2. Image color separation content quality inspection

Image color separation content quality inspection consists of layers, colors, and sharpness.

(1) Inspection of hierarchical replication

There are two aspects to the hierarchical replication check. The first is to check the correctness of the overall tone control of the image, and whether the various color levels can meet the printing requirements of the manuscript; second is whether the high-profile, intermediate tone and shadow tone levels of the image reflect the purpose and requirements of image reproduction. Whether the adjustment is accurate and whether the transmission is reasonable, the main inspection parameters are (1) image highlight record dot size, (2) dark tone record dot size, (3) black version high and low dot size, (4) high, medium, low profile Whether the image level distribution is consistent with the original and copying requirements, (5) whether the extremely high light processing is accurate.

(2) Inspection of color reproduction

The color copy check is to check if the percentage composition of the Y, M, and C color dots is appropriate. The main contents are (1) whether the gray balance reproduction is correct, that is, the percentage of dots in the neutral gray region of the high, medium, and low parts of the image is examined. Accuracy. (2) The effect of color correction is to check whether or not the color point has reached the set dot value. (3) Character color inspection. Normally, the basic rule of color arrangement in the face with normal skin tone is dark tone. The yellow plate should not be deeper than the magenta version, that is, Y% ≤M%. Forehead, the Y% is slightly larger than M%, and the cheek area is Y% <M%. For the forehead, Y%=M%. Care should be taken in the color separation check (1) The yellow version is the foundation of skin color, and the skin color is expressed by the strength of the yellow version. Therefore, the color quantity of the yellow dot network should be accurate at all levels, and the areas of high light and light gradation should be flawed, and there should be level changes. Never avoid peace. The yellow version of the pan-colored area needs to be changed, and the percentage of the yellow version of the dots at the light spot should be less than the percentage of the magenta dots. (2) The magenta version is the main color version of the skin. It requires delicate smoothness and an appropriate amount of color. Attention should be paid to the control of the overall color amount based on the inherent color of the facial midtones. At the same time, the facial regions should have levels and color changes. , guarantee the deepest lips, followed by cheeks, the amount of the standard, the forehead is bright, and the high light spot never stops netting. And should be flexibly adjusted according to the characteristics of the original character. (3) The focus of the Cyan version is to show the level of facial contours, the contrast between light and shade, and the change of color and coldness and set off the main body. When checking, attention should be paid to the overall facial brightness and darkness, facial contours, and the combination of skin tones and cyan plates and highlights. In the high-light area, the cyan version generally does not need to be netted, leaving sharp points. (4) The black version of the main character should be black and white. It is usually high-profile and the intermediate tone area should be netted. Second, the electronic color film defect trimming Electronic color film defect repair is mainly to solve the defects of the original surface electronic color separation machine can not fully compensate for the lack of customer requirements for local changes and artistic processing needs. Frequently, it adopts dot corrosion repair, dry dot repair, color manuscript trimming, dot etch and other techniques. Trimming operators must accurately understand and master the color reproduction theory and electronic separation printing plate printing rule, have a higher ability of art appreciation and analysis, and have superb skills in repairing the plate, can the correct treatment of the color separation film and ensure the reproduction of the figure Image quality is stable and perfect.