Generating CMYK Separations
Color Separation - Generally refers to conversion from any color space (model) other than CMYK to CMYK. A good separation is necessary to reproduce colors by conventional process colors. (With the advent of extended colors such as Pantone Hexachrome and TransCal HiFi, this term is coming to be used for separations into these extended process color spaces as well.)
- Conversions between the CIE based systems are relatively simple. Since they are device independent they never change and basically, all of them are equivalent.
- Conversion between device dependent models is more difficult since information about different display and output devices must be used to do the conversion.
- Conversion to CMYK, particularly from RGB, is far from simple. It depends on the monitor phosphors, white point temperature and gamma as well as the ink pigments, assumed dot gain and gray component replacement (GCR, we’ll explain this later). We illustrate this with the color picker in Photoshop.
- With all this complication, how can we expect to achieve good color reproduction with good color balance and contrast with saturated colors? More importantly, how can we get good reproduction of critical colors such as memory colors and identity colors?
- Sometimes the conversion between two device dependent spaces is too easy for the user because the software hides the difficulty. You just click the menu.