Digital screens render color using an additive light model (Red, Green, Blue). Print hardware utilizes a subtractive ink model (Cyan, Magenta, Yellow, Key/Black). Transforming a document designed for screens (sRGB) into a print-ready format (PDF/X) requires careful gamut mapping.
Gamut Clipping
The sRGB gamut is significantly larger in the vibrant spectrum than the standard CMYK gamut (SWOP or GRACoL). When an sRGB document contains highly saturated blues or greens, a conversion engine must "clip" those colors to the nearest printable equivalent. This results in dull, muddy colors on the physical page.
Intent and Rendering Profiles
When converting color spaces, ICC (International Color Consortium) profiles dictate the transformation. The Rendering Intent tells the engine how to handle out-of-gamut colors:
- Perceptual: Compresses the entire gamut so relationships between colors remain intact. Best for photographs.
- Relative Colorimetric: Maps out-of-gamut colors to the closest printable edge, leaving in-gamut colors alone. Best for logos and vector graphics.