Comparing Color Profiles
Ever wonder why when you convert an image from RGB to CMYK, the color appearance can be so dramatically different?
One way to understand why this happens is to compare the color space gamuts of different devices (such as a display and a printer). You can do this by using the ColorSync Utility.
Step 1: Open the ColorSync Utility, located in the Utilities folder in the Applications folder, and click Profiles in the toolbar.
Step 2: In the left column, select the color profile of your first device. Youll then see in the bottom-right space a 3D model called a lab plot.
Step 3: Click the downward-pointing triangle on the top-left corner of the lab plot, and from the pop-up menu choose Hold for Comparison.
Step 4: Then click the profile of another device in the left column.
Youll now see the color profiles of the two different devices laid on top of each other. The first profile you held for comparison is the lighter of the two.
Comparing the three-dimensional gamut of the selected profiles shows you how converting from one color space to another can affect the colors of your image. The areas where one gamut exceeds the boundaries of another are known as out of gamut. These out-of-gamut colors which cannot be reproduced within the target color space (or on the target device) cause the difference in appearance when converted from color space to another.

