I've been looking for a blend mode to (well ...) blend two RGB pixels in order to build colors in the samw way that a painter builds them (i.e: subtractive).

Here are quick examples of the type of results that I'm expecting:

CYAN + MAGENTA = BLUE
CYAN + YELLOW = GREEN
MAGENTA + YELLOW = RED
RED + YELLOW = ORANGE
RED + BLUE = PURPLE
YELLOW + BLUE = GREEN

I'm looking for a formula, like: dest_red = first_red + second_red; dest_green = first_green + second_green; dest_blue = first_blue + second_blue;

I've tried with the commonly used 'multiply' formula but it doesn't work; I've tried with custom made formulas but I'm still not able to 'crack' how it should work. And I know already a lot of color theory so please refrain from answers like:

Check this link: http://the_difference_betweeen_additive_and_subtractive_lightning.html