Color Printing Software Proofing Quality Management Solution II

2. Adobe Gamma software screen correction This is a method we are all familiar with. It is also to set the optimal brightness and contrast of the screen with the help of the software visual bar, and then set the color temperature (ie, the white point, the requirement and the display's hardware set the same color temperature, generally 5000K or 6500K) and Gamma (Window system Generally 2.2), and then through the corresponding visual bar and adjustment function for optimal adjustment of Gamma and color temperature in order to achieve the best, after the formation of a screen profile can be used by the color management process. This parameter-type profile is less effective than a hardware system because of its limited accuracy and direct visual adjustment.

Set appropriate color management processes and mapping methods The color management process is used to implement and control the color space conversion of various colors. For the color newspaper professional production line, the most economical and reasonable color management process based on screen soft proofing should be the use of color management functions built into prepress software such as Photoshop and CoreIDRAW.

Photoshop's built-in color management process, where "View -> Proof Color" initiates the soft proofing effect, and "View 1> Proofing Settings" is used to select the simulation object and intent. It uses the RGB-Lab-CMYK-Lab-RGB (for RGB color) or CMYK-Lab-RGB (for CMYK color) processes shown in FIG. 2 to complete screen emulation of the output of RGB files and CMYK files. Its characteristic is that the RGB color space must be converted to the color newspaper CMYK color space to be "constrained", and then converted to the RGB color space again to display the "constrained" color and image effects, thereby providing the screen display with the printing effect for the editing.

In CoreIDRAW, it can directly provide a color management control process based on screen soft proofing. It first converts the Lab color value to the CMYK printing color space, and then converts it to the corrected screen and the RGB color space represented by the Profile and displays it to form a simulation effect. Another important issue is the choice of mapping methods. The mapping method is mainly to solve the two core issues of color space compression and white point transfer. Sataration (saturation) and Perceptual (perceivable) can convert the white point of the source color space into the white point of the target color space, while Absolute (absolute) simulates the white of the source color space in the target color space. point. For screen soft proofing, if it is a screen emulation of the RGB file's color report effect, the white point of the RGB color space needs to be converted into the white point of the CMYK color space by using the Relative, Sataration, and Perceptual methods so as to be on the screen. See the effects of different paper whiteness. If it is a CMYK file, Absolute mode is needed to “pass” the white point of the CMYK color space onto the screen to form the background color emulation effect of newsprint.

Use of pre-standard processing methods and effect standards After the soft proofing process has been established using the above method, both pre-screening and pre-press processing of color and image effects should be WYSIWYG. The small print gamut that is unique to newsprint (reflected as lower saturation and brightness) and the more varied paper whiteness (color shift) can be reflected on the screen, and the effect of adjustment is not necessary. Worry about not printing. In terms of quality requirements, following the industry standards for color newspapers, there are the following requirements:

(1) Ink requirements: full and moderate, pure hue, no color cast.
(2) The image quality requirements: clear, moderate contrast; the image is not false, good resolution, can restore the natural tone.

To achieve these requirements can be summarized into the following standardized processes:
(1) Black and white fields and contrast processing: It mainly controls the overall tonal range and image range, and implements the “separation of layers.
(2) Treatment of color shift and saturation: The control of "full and moderate, pure hue, no color cast" is implemented.

The processing method is as follows:

1 Use a pipette tool to neutralise the color cast. The color shift can be determined from the neutral gray region of the image, and the dropper is used to target the region as neutralization of the gray level, that is, the neutral gray region of the color shift is set with a neutral value.
2 Use the Hue/Saturation tool for vivid color control.

(3) Sharpening: Implementing the control that "the image is good and the resolution is good". The quality of newspapers' artwork submissions varies greatly, especially in terms of clarity and resolution. The processing method is to use the SUM sharpening tool. Hot stamping process in the hot stamping foil is how to do

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[hc360 HC Network Printing Industry Channel] In the process of designing and developing new products, craftspeople often use a special hot stamping process to highlight the product theme, that is, the first hot stamping process. In the course of this process, hot stamping foils are often pulled back by printing inks, which not only seriously damages the design effect but also is very disadvantageous to the printing equipment. Because the hot-stamped foil powder that is pulled back quickly accumulates on the blanket, the image dots will be lost if it is light, and the partial image will not be printed when it is heavy.

Not only that, the hot stamping foil powder will reach the ink roller by transferring, accelerating the wear of the ink roller, and causing damage to the printing equipment. From the above analysis, we can see that if you want to use the first hot post-printing process, you must put an end to the problem of the hot stamping foil being pulled back during the printing process. Solving the problem of the hot stamping foil being pulled back can start from the following two aspects.

1. Hot Stamping Quality Control Hot stamping quality is a prerequisite for ensuring that the subsequent printing production runs normally. First, according to the different surface properties of paper, choose the right hot stamp foil. The electro-foiled aluminum foil after stamping generally has a great contrast with the background, and there is no need to worry about the effect of hot stamping. The key is to ensure that the hot stamping foil is firmly attached to the surface of the paper.

To achieve this goal, in addition to the hard work of selecting stamping foils, it is necessary to strictly regulate the operating procedures of the staff. In addition to the requirement of machine personnel to control the hot stamping temperature, the hot stamping pressure and the hot stamping speed, it is more important to regularly test the adhesion of the hot stamping layer. Because in the hot stamping process, the adhesion between the hot stamping layer and the paper may change as the number of hot stamping increases.

Adhesion test using glue test method specifically: the tape was glued to the hot stamping layer, quickly pulled off the tape. In general, if the hot stamping layer cannot be pulled off, the problem of ink reversal hot stamping foil does not occur during printing. If the hot stamping layer is pulled off by the tape, it indicates that the hot stamping layer is not firmly attached and the pressure correction process needs to be performed again. When the school pressure reaches a certain number of times, the stamping quality tends to be stable.

2. Control of the printing process Generally, the viscosity of the offset ink is relatively high, and the pulling force on the surface of the paper is large during the printing process. This contradiction can be alleviated by appropriately reducing the viscosity of the ink. In addition, in the case of normal printing, the printing pressure is as small as possible.