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Upvotes for the subtractive/additives! Pigments are designed to absorb + selectively reflect photons (select out of the spectrum) Screens are designed to emit photons (blend into the spectrum) The problem with matching colors between displays and hardcopy is a major reason why print process use CMYK (Cyan, Magenta, Yellow, blacK). This is Not Yellow (VSauce, ~7 minutes; FYI, the video wanders around into other topics) https://youtu.be/R3unPcJDbCc "You are seeing fake yellow...how screens trick your brain"
Primary colors system with 'blue', red' and 'yellow' as you learn at school for paint mixing, is not accurate at all, and the reverse system of the one use for screen color mixing... Real primary colors of painting is better described by names used by printer ink: CMYK stand for 'cyan' , 'magenta', 'yellow' and black (we used black and white also at school ^^), and real 'red', 'green' and real 'blue' are the complementary colors of the first, the one used on screen. By using RGB, you can evaluate color mix with these few new rules: R + G == Yellow R + B == Magenta G + B == Cyan R + G + B == full luminosity == White none == screen off == Black
The key difference is here: when you are mixing paint, you are using a substractive system colors (the more you use paint, the less your paper is white and you reach near the black by mixing all), but when you are mixing screen color you use an additive one (no light at all give black, full all like give white) ^^
Alomg with Visph's answer, a computer displays color based on light. So, when mixing inks, you have a different color spectrum; when mixing light values, you are then in another spectrum, and the same goes for paints and designs and other things.
when mixing Red and green, both are dark colours, one shouldn't get a brighter colour. The logic is ass backwards.
again, this is fascinating