How to Select a Color Mode in Photoshop CS6
In Adobe Photoshop Creative Suite 6 you can enhance your images by adjusting the color mode. Every file has a color mode, also called an image mode or just plain mode. To determine the color mode of an image, look in the title bar of the image window or choose Image→Mode.
Color modes define the color values used to display the image. Photoshop offers eight modes and enables you to convert images from one mode to another. The color mode you choose for a particular image depends on a couple of factors:
The file format you plan to save it in: Some modes call for specific file formats. You may find that a certain format is unavailable because your file isn’t in the appropriate color mode.
The end use for the image: Do you plan to post the image on the web? Or are you putting it in a brochure that will be offset printed?
To really understand color modes, you need a basic understanding of RGB and CMYK color theory. When you view an RGB image, you’re looking at an image made of three colors — red, green, and blue.
Red, green, and blue are
The primary colors of light (additive color)
The colors that correspond to the three types of cones inside your eyes
The colors that comprise white light from the sun
The colors your monitor uses when displaying images
The CMYK color scheme (subtractive color) is based on the light-absorbing quality of ink on paper. In theory, a white light hits these inks. Some visible wavelengths are absorbed, or subtracted, and others are reflected back to your eyes. CMYK images comprise various percentages of only four colors of ink — cyan, magenta, yellow, and black (CMYK). These colors correspond to the inks used in the offset printing process.
Color modes affect the number of colors that display, as well as the size of the file and the number of channels. One or more channels — in which the color data is stored — represents each mode. Grayscale images have one color channel — Black. CMYK images have four color channels — Cyan, Magenta, Yellow, and Black.