About color management

Introduction to color management

Sometimes the colors in the same image will look different on different monitors. The color of an image printed with a desktop printer may look very different from the color of a printed image in a publication. If you need to generate consistent colors between different devices, you should use color management as an important part of your workflow.

Why the color will change

We use color models to describe the various colors seen and processed. Each color model (for example, RGB, CMYK, or Lab) represents different methods for describing colors and classifying colors, respectively. The color model uses numerical values ​​to represent visible chromatograms. Color space is another form of color model that has a specific color gamut. For example, there are multiple color spaces in the RGB color model: Adobe RGB, sRGB, and Apple RGB. Although these color spaces use the same three axes (R, G, and B) to define colors, their color gamut is not the same.

All devices operate in their own color space, which is the range of colors they can reproduce. No device can reproduce all the color ranges visible to the human eye, nor can there be two devices with exactly the same color space.

When you manipulate image colors in Adobe Photoshop, you are actually adjusting the values ​​in the file. You can easily think of a number as a color, but these values ​​are not absolute colors themselves, and they only have a certain color meaning within the color space of the device that generated the color.

Because each device has its own unique color space, they can only reproduce the colors in their own gamut. When moving an image from one device to another, the color of the image may change because each device interprets the RGB or CMYK value according to its own color space.

Each device has a different color space.
The colors printed by the desktop printer cannot be exactly the same as the colors seen on the monitor. The printer operates in the CMYK color space, and the monitor operates in the RGB color space, with different color gamuts. Some colors produced by the ink cannot be displayed on the monitor, and some colors displayed on the monitor cannot be reproduced on the paper with ink.

The color space of each device interprets the same RGB values ​​in different ways.
Although it is not possible to have all colors on different devices match exactly, you can use color management to ensure that most colors are the same or similar to achieve a consistent rendering effect.

Use color management to solve color inconsistencies

With color management, you can generate a system-consistent color that harmonizes the color space differences between devices.

In order for the color management system to successfully convert color values ​​between different color spaces in order to preserve the same or very similar colors, the following three conditions must be met:

The color management system must know the color space of the image in order to understand the meaning of the color values ​​in the image. When you assign a profile to an image, the image must be in the color space described by that particular profile. The document's configuration file can be specified by the source device (such as a digital camera or scanner) or specified in Photoshop.
Second, the color management system uses color patches to identify the absolute color represented by the color values ​​in the image. Currently, color management systems use CIE L*a*b* (Lab) or CIE XYZ as the color code. Both color spaces describe all the colors that the human eye can see; the color values ​​referenced within the space are not limited to the colors generated by any device, nor are they just related to the colors generated by a certain device.
Finally, the color management system must know the color space of the target device in order to send the correctly converted RGB or CMYK color values ​​to the device. The color management system uses a configuration file to understand the specific meaning of the RGB and CMYK values ​​for each device. The device configuration file can be provided by the manufacturer, or it can be created by third-party software and hardware.

Color Management A. The source device creates a document containing the original color value B. The source profile describes the color space of the device, the document profile describes the color space of the document C. With the original color values ​​and profile data, the color management system can use Lab to identify the actual color in the document D. The device profile describes the color space of each device E. The color management system converts the original color values ​​to the color space of each device

Basic steps to generate a consistent color

The color management system is built into Photoshop. To successfully use Photoshop's color management system, you need to follow some basic steps.

Start managing colors in your workflow:

Calibrate the monitor. Use an intuitive calibration method, such as Adobe Gamma® (Windows) or Display Calibrator (Mac OS), or use third-party software and hardware for more accurate calibration.
Specify color settings when you first start Photoshop. The color settings in the Photoshop Color Settings dialog box control how RGB, CMYK, and grayscale images work in the color management system.
The first time you start Photoshop, the system displays a warning message stating that the default settings (web graphics defaults) will be used to configure the color settings and asks if you want to customize the color settings. Do one of the following:

Tap No to accept the default settings. Keep in mind that the default settings may be suitable for maintaining a consistent color for images displayed on a computer monitor, but not necessarily the best choice for printing images.
Note: Although it is not necessary to customize the color settings the first time you start Photoshop, it is recommended that you do so. The choices you make in the Color Settings dialog box affect how the image colors are displayed.

For better control of the Photoshop color management system, click Yes when you first start Photoshop to customize the color settings in Photoshop. This will open the "Color Settings" dialog box. In the Color Settings dialog box, choose preset options from the Settings menu. If you are printing an image on a desktop printer or press, select one of the prepress defaults associated with your region. For example, if you are in the United States, you should select United States Prepress Default Settings.
If you want to have maximum control over the Photoshop color management system, click Yes when you first start Photoshop to customize the color settings in Photoshop. This will open the "Color Settings" dialog box. In the Color Settings dialog box, select the Advanced Mode option and specify the settings.
Note: If you click No, the Color Settings dialog is not displayed at this time. This dialog box can be accessed at any time by selecting (Windows) Edit> Color Settings or (Mac OS) Photoshop> Color Settings.

In order to maintain consistent colors among other applications for color management (such as Adobe Illustrator, Adobe InDesign, and Adobe Acrobat®), it is important to use the same color settings in these applications. Keep in mind that colors between color-managed applications and non-color-managed applications may not match. For more information about synchronizing color settings between color-managed Adobe applications, see Maintaining consistent colors between Photoshop and other Adobe applications.

Create or get the configuration file for the device used in the workflow, such as a desktop printer. The Photoshop color management system needs to understand how the devices used in your workflow work so that the color values ​​in the document can be converted correctly, so that all types of devices produce a consistent color. Common methods for obtaining a configuration file include:
Install the desktop printer driver. When installing the printer driver, the configuration file is usually installed on the computer system. The color management system can access this profile, so when you print from Photoshop, the profile appears as a color management option.
Create a configuration file using third-party measurement tools and software. This method creates a more accurate description of how a particular device works.
Note: You should also create a separate profile for each type of paper used in your desktop printer. Smooth paper and non-smooth paper display a different range of colors. Use a third-party measurement tool and software to generate custom paper profiles.

Incorporate color management into various workflows. Unless you know how to use calibrated monitors and configuration files, they have no effect:
If you want to maintain consistent color when printing to inkjet printers, dye sublimation printers, laser printers, or any desktop printer, see Using Desktop Printers to Generate Consistent Colors.
If you want to make the colors displayed in a typesetting application (such as InDesign) consistent with the colors printed by the printer, see Producing consistent colors when sending images to the press.
If you want to maintain a consistent color when you create images for Web browsing or for multimedia presentations, see Producing consistent colors when you create images for the Web.