Rewire how the three color channels feed the final image. Every output channel takes a weighted sum of the red, green, and blue source values, which covers jobs a hue slider cannot: swapping channels outright, correcting one channel from the others, or building a black and white conversion with full control over which colors carry the tone.
The mixing matrix
The tool edits one output channel at a time. Select Red, Green, or Blue, then set how much each source channel contributes, anywhere from -200% to 200%. The identity settings (100% from the matching channel, 0% from the rest) leave the image untouched, so every edit is a deliberate departure from a known neutral.
Negative weights subtract. A red output of 150% red and -50% blue increases separation between warm and cool regions, a move familiar from color-negative correction.
Channel swaps
Some conversions are pure rewiring. Aerial and infrared photography commonly swaps red and blue: set the red output to 100% blue, the blue output to 100% red, and foliage rendered in false color flips from red to the expected blue-cyan. Since each row is independent, partial swaps work too, blending a channel into its neighbor rather than replacing it.
Monochrome conversion
Monochrome mode reduces the mixed result to luminance, and the matrix decides the gray values. Weighting red up mimics a red lens filter on black and white film: skies darken, skin lightens. Weighting green favors natural midtone separation, and a heavy blue mix produces the harsh tonality of early orthochromatic photography. This is the control a plain grayscale toggle hides from you.
Keeping brightness stable
There is no automatic normalization. A row summing far above 100% clips toward white, one far below sinks toward black. That headroom is intentional, but when a mix is meant to stay tonally faithful, keep each row’s total near 100% and check the extremes of the histogram in the preview.