Color space conversion settings for prepress output images

The image file used for printout must be CMYK color mode, not RGB mode. The process from RGB mode to CMYK mode is what we call the separation process. Although this operation is very simple, but really want to color separation to meet the actual conditions of the printing, you must do a good job in the color separation parameter setting work. Separation parameter settings are essentially part of the color management process. After Photoshop version 5.0, the color separation parameters were set to color management.

Start Photoshop software, open the Edit -> Color Settings command, set the CMYK workspace in the workspace settings, you can choose Photoshop's built-in CMYK color space, you can also set the user according to the actual print output conditions.

Grayscale space setting

It has a great influence on the value of converting from color mode to grayscale mode (GrayScale). For example, 20% identical RGB color R75G128B56, Dot Gain is selected, converted to a numeric mode K GrayScale 65%; 25% Dot Gain is selected, converted to a numeric mode K GrayScale 60%; is selected Dot Gain At 30%, the value K converted to GrayScale mode is 54%.

Spot color space settings

It directly affects the display color of spot color images. If Dot Gain is 20%, a spot color percentage of 55% is brighter. When Dot Gain is changed to 30%, the color is darker.

Color Management Solution

In order to manage colors more effectively through systems and applications, Photoshop can embed ICC color profiles in image files. After inlining, the ICC Profile can describe the correct color space for image files and ensure color consistency. When other applications open the image of the embedded ICC Profile, if the relevant settings and embedded inconsistencies, will automatically determine and decide what to do. In previous versions of Photoshop, the "Profile Settings" was used to embed ICC Profile files. Photoshop 7.0 changed this and changed the ICC Profile embedded work when storing image files. If it is an RGB image, the inline is embedded according to the settings of the above RGB space, and if it is a CMYK image, it is embedded according to the setting of the CMYK space.

When opening an image file in other application software, what happens if the ICC Profile embedded in the image does not match the software settings, or if the image does not have the ICC Profile embedded? This is the problem to be solved by the Color Management Polices. In Edit -> Color Settings dialog box contains the color of the content management program (color management policies), the relevant settings shown in Figure 6, where respectively to RGB, CMYK, Gray image set, but the basic content is the same.

Photoshop color space conversion method settings

Open the Edit -> Color Settings dialog box, select the "Advanced Mode" at the top of the dialog box. At the "Conversion Option", you can choose the color space conversion. The color management engine (Engine) and the color conversion method (Intent) for color space conversion are selected.

Basic settings for Photoshop color management

Open the Edit -> Color Settings dialog box. At the top of the dialog there is a "Settings" drop-down menu, which mainly determines what kind of color management settings to use. Specific settings include "Color Management Off", "Photoshop5's default color space", "Web Graphics Default Settings", "U.S. Prepress Default Settings", "European Prepress Default Settings", etc., which operators can use at their discretion. If there are changes to these settings, it is a custom setting.