Duotone Converter
Map every pixel's brightness onto a two-colour gradient. Pick the shadow and highlight inks, slide the midpoint, and dial in contrast — the conversion happens entirely in your browser.
Drag & drop an image here, or pick a file
PNG, JPG, GIF, WebP, AVIF — nothing is uploaded
Low values give a posterised two-tone look.
Current palette: Midnight
Your duotone preview will appear here.
About this tool
Duotone Converter measures each pixel's Rec. 709 luminance, applies your contrast curve around the midpoint, then offsets the result across a two-stop gradient between the shadow and highlight inks. Softness controls how wide that gradient is, so a low value gives the flat, posterised two-colour look while a high value keeps smooth tonal separation. Photos are capped at 2000px for speed and the whole conversion runs in your browser — nothing is uploaded.
- 100% free — no account needed
- Runs in your browser
- Nothing is uploaded
Frequently asked questions
Is Duotone Converter really free?
Yes. Duotone Converter is completely free on PureBrowser — every feature, with no account, no trial, and no credit card.
Does Duotone Converter upload my data?
No. Duotone Converter runs entirely inside your browser, so anything you type, paste, or open stays on your own device.
Do I need to sign up or install anything?
Neither. There is no account and nothing to download — open the page and Duotone Converter is ready to use on desktop or mobile.
Does Duotone Converter work offline?
Once the page has loaded, yes. All of the processing happens locally in your browser, so it keeps working without a connection.
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