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Toolcroft

Image Tools

Duotone Image Generator - Two-Color Photo Effect

Apply a duotone effect to any image: choose a shadow color and a highlight color and the tool maps the entire photo to a two-color palette. Download the result as PNG.

About the duotone effect

Duotone became widely recognised through Spotify's promotional artwork, where music artists are displayed in vivid two-colour washes. The effect traces back to early screenprinting and offset lithography, where reproducing a full-colour photograph was expensive, so printers used two inks to simulate a tonal range.

How it works

The tool converts each pixel to a luminance value using the standard BT.601 formula: Y = 0.299R + 0.587G + 0.114B. Each channel is then linearly interpolated between the shadow color (luminance 0) and the highlight color (luminance 1).

Choosing good color pairs

High-contrast complementary pairs produce the most striking duotones. Popular combinations include deep navy + warm amber, magenta + cyan, forest green + cream, and dark violet + neon yellow.