Channel mixer
With the Channel Mixer you build an output channel from a mix of the red, green and blue channels. You decide how much each channel contributes, for color correction or a rich black and white conversion. It gives a lot of control over how colors translate into grayscale.
Add the Channel Mixer as an adjustment layer and tick Monochrome for black and white, or leave it off for color work. With the sliders you set how light or dark each color becomes, like a deep sky by toning down blue. Keep the sum of the sliders around 100% to keep the brightness right. Tip: for black and white with character, the Channel Mixer often gives nicer tonal separation than a simple desaturation.
Related terms
Prefer a look in one click?
The presets on this site set these adjustments up for you as a starting point, which you then fine-tune to taste.