What happens when RGB is converted to CMYK?

When converting from RGB (Red, Green, Blue) to CMYK (Cyan, Magenta, Yellow, Black), several key transformations and challenges occur because these colour models are fundamentally different:

1. COLOUR MODEL DIFFERENCES

    • RGB: Additive colour model used for light-based displays (e.g. screens). It creates colours by adding red, green, & blue light.
    • CMYK: Subtractive colour model used for printing. It creates colours by subtracting light using cyan, magenta, yellow, & black inks.

2. GAMUT SHIFT

    • RGB has a wider gamut (range of colors it can represent) compared to CMYK.
    • Some colours in RGB, especially bright neon colours and very vibrant hues, cannot be directly reproduced in CMYK. These colours are “out of gamut.”
    • Result: Colours may look duller or slightly different in CMYK compared to their RGB counterparts.

3. COLOUR MIXING

    • RGB mixes light to create white, while CMYK mixes pigments to create black.
    • In CMYK, black (K) is added separately for depth and cost-efficiency, as mixing cyan, magenta, and yellow alone doesn’t produce a pure black.

4. BLACK COMPONENT (K)

    • In CMYK, the black ink (K) is used to create shadows, detail, and contrast, reducing the reliance on mixing the three other colours (C, M, Y).
    • During conversion, a process called “black generation” determines how much black ink is used instead of combinations of C, M, & Y.

5. POTENTIAL COLOUR LOSS

    • Bright, saturated colors and light

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