Darken compares the colors you are painting with to the layer underneath and keeps the darker color without blending them together.
The Math
The colors of the Darken layer are compared pixel by pixel to the color of the base layer for each RGB channel. The lower number is selected, and since lower numbers mean darker colors, the result can only get darker (or stay the same) in this blending mode.
Mathier Math
RGB colors are represented by three numbers: one for red, one for green, and one for blue. Each channel is compared separately using the minimum function:
Result = min(Top Layer, Base Layer)
So if the top layer has an RGB value of (80, 200, 150) and the base layer is (120, 160, 180), Darken compares each channel:
- Red: min(80, 120) = 80
- Green: min(200, 160) = 160
- Blue: min(150, 180) = 150
The resulting color is (80, 160, 150).
When you use Darken, there are three tiny math problems happening for every pixel!
Core Rules of Darken Mode
White disappears: Pure white on the top layer is the highest possible brightness value, so it is always ignored, letting the base layer show through completely.
Black wins: Pure black on the top layer is the lowest possible value, so it completely replaces whatever color is underneath.
No color mixing: Unlike Multiply, which multiplies color values together to create deeper secondary tones, Darken simply picks the lower value from each RGB channel.
When to Use It
Selective application: Painting with a lighter color has no effect, allowing you to paint broadly while only affecting areas where your strokes are darker than the underlying image.
Ink and textures: Placing a texture or ink wash on a Darken layer lets the dark areas interact with the art while white areas disappear, allowing the lighter areas of the base layer to remain visible.