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About color management


    Because color-matching problems result from various devices and software that use different color spaces, one solution is to have a system that interprets and translates color accurately between devices. A color management system (CMS) compares the color space in which a color was created to the color space in which the same color will be output, and makes the necessary adjustments to represent the color as consistently as possible among different devices.

    Note: Don't confuse color management with color adjustment or color correction. A CMS won't correct an image that was saved with tonal or color balance problems. It provides an environment where you can evaluate images reliably in the context of your final output.

    Photoshop follows a color management workflow based on conventions developed by the International Color Consortium (ICC). The following elements and concepts are integral to such a color-managed workflow.

    Color management engine

    Different companies have developed various ways to manage color. To provide you with a choice, a color management system lets you choose a color management engine that represents the approach you want to use. Sometimes called the color management module (CMM), the color management engine is the part of the CMS that does the work of reading and translating colors between different color spaces.

    Color numbers

    Each pixel in an image document has a set of color numbers that describe the pixel's location in a particular color mode--for example, red, green, and blue values for the RGB mode. However, the actual appearance of the pixel may vary when output or displayed on different devices, because each device has a particular way of translating the raw numbers into visual color. (See Why colors sometimes don't match.) When you apply color and tonal adjustments or convert a document to a different color space, you are changing the document's color numbers.

    Color profiles

    An ICC workflow uses color profiles to determine how color numbers in a document translate to actual color appearances. A profile systematically describes how color numbers map to a particular color space, usually that of a device such as a scanner, printer, or monitor. By associating, or tagging, a document with a color profile, you provide a definition of actual color appearances in the document; changing the associated profile changes the color appearances. (For information on displaying the current profile name in the status bar, see Displaying file and image information.) Documents without associated profiles are known as untagged and contain only raw color numbers. When working with untagged documents, Photoshop uses the current working space profile to display and edit colors. (See About working spaces.)