Duotone Image Generator - Two-Color Photo Effect

How to use this tool

Upload an image using the file picker or drag-and-drop.
Choose a shadow color (dark tones) and a highlight color (bright tones).
Click Download to save the duotone image 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.

Frequently asked questions

What is a duotone effect?

A duotone converts a full-colour image to greyscale, then maps the darkest tones to one colour (the shadow) and the brightest tones to another (the highlight). The result is a two-colour image popular in branding and poster design.

Which image formats are supported?

You can upload JPEG, PNG, WebP, and GIF files. The output is always downloaded as PNG to preserve quality.

Does the image get uploaded anywhere?

No. All processing happens entirely in your browser using the Canvas API. Your image is never sent to any server.