Differeces in RGB and CMYK

RGB is the primary color model used by display devices.
CMYK is the primary color model used by color printers.

In RGB, images are created by using Red, Green, and Blue light. This process can create millions of different colors by using different concentrations of the primaries.

CMYK, in contrast, creates different colors in a subtractive process mixing four colors or inks: Cyan (blue), Magenta (red), Yellow, and Black.

CMYK works by removing color from a white background, whereas RGB adds color to a black background. CMYK pigments absorb most of the white light that hits them, reflecting only part of the spectrum back to the eye. Similarly to RGB, CMYK creates various colors by combining the Cyan, Magenta, Yellow, and Black inks in different proportions.

The differences between RGB and CMYK become crucial when desktop publishers attempt to move documents from their screens onto hard copy. There are many RGB colors that CMYK printers cannot reproduce. To overcome this limitation, many applications allow you to work with an image by specifying CMYK color instead of RGB. On the hardware side, high-end printers can supplement CMYK inks with specific spot color inks that improve the printed output's fidelity to the original.