Duotone Generator

Map an image's tones between two colors and export PNG. Free, runs entirely in your browser — no signup, and nothing you paste in is uploaded.

A duotone maps the image's tonal range onto a gradient between two colours: convert to luminance, then use that single value to look up a colour between the shadow and highlight ends. It is a printing technique from when two inks were cheaper than four, and it survives because it forces an image to agree with a brand palette.

It works best on photographs with a clear tonal range and clear subject separation, and poorly on flat or low-contrast images, where collapsing to one luminance channel leaves nothing for the gradient to distinguish. High contrast between the two chosen colours generally reads better than a subtle pair.