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Color Schemes: CMYK vs. RGB
RGB (Red, Green, Blue) is the color scheme used in computer graphics. CMYK (Cyan, Magenta, Yellow, Black or “Key”), on the other hand, is the standard for printing color images. The computer screen displays light. As colors are added in RGB, light is added as well. Alternately, the CMYK color scheme is used in combining inks. Therefore, as more colors are combined, the resulting color becomes darker.
If you are working in RGB, you must convert your promotional printing files from RGB to CMYK so that they can be printed on a printing press. Unfortunately, not all colors can be replicated in the transfer process. While some colors may be out of the CMYK gamut, it is usually difficult to tell the difference in full color fine art printing.
So what the differences?
RGB uses the colors red, green, blue which are the primary colors of light. The secondary colors to these are cyan, magenta, and blue, which can be found in CMYK. Therefore, CMYK is opposite RGB.
Both RGB and CMYK modes use 8-bit channels for each of their colors. Since RGB includes 3 colors, RGB is a 24-bit model. CMYK, on the other hand, uses 4 colors, and therefore it is a 32-bit model.
The RGB process of color is additive. The colors throughout the color spectrum are created in RGB by adding different intensities of red, green, and blue light to black. Black is equivalent to no light on the computer screen. The intensities of RGB light can be as weak as 0, or as strong as 255.
The CMYK process of color is exactly the opposite. As RGB light is striking an object, CMYK colors are absorbing the light and reflecting back appropriately. The amount of light absorbed depends on the amount of CMYK color present. Therefore, CMYK is considered a subtractive process. The colors displayed by CMYK are the result of subtracting varying amounts of red, green, and blue light.
When your promotional printing project uses custom RGB printing, the eye sees the varying light of red, green, and blue (and all the colors they produce) before they are absorbed. When you produce Giclee printing in CMYK, however, we are seeing the color lights that have been reflected back to us after absorption.
This is just more proof that full color photo printing is an amazing and intensely detailed process.
Filed under: Uncategorized, Design, Education, File Preparation, Technology, Digital C Print on December 19th, 2007