Adjustments

Duotone

Transform any image into a striking two-color duotone with custom shadow and highlight colors. The effect maps dark tones to one color and light tones to another, producing bold editorial and graphic design aesthetics. All processing runs locally on your self-hosted server.

Deploy with Docker View Source

Features

  • Custom hex color selection for both shadow and highlight tones
  • Smooth tonal mapping that preserves image detail and contrast
  • Works with photographs, illustrations, and mixed-content images
  • Preserves original resolution and outputs in common image formats
  • Real-time preview of color combinations before processing

What you can do

  • Creating on-brand hero images using company colors for a marketing website
  • Designing duotone poster artwork for events, concerts, and social campaigns
  • Applying a consistent visual style across a batch of blog post header images
  • Producing retro-styled photo effects for print zines and editorial layouts

Self-hosted. Your files never leave your network.

SnapOtter runs entirely on your own infrastructure. Files processed with Duotone are never uploaded to third-party servers. Deploy a single Docker container and process files with full privacy, no watermarks, and no usage limits. Open source under AGPL-3.0.

Frequently asked questions

Can I use any two colors I want?
Yes, both the shadow and highlight colors are fully customizable via hex color values. You can match your brand palette exactly, and since SnapOtter is self-hosted, you can iterate on combinations freely.
Does the effect work well on photos with lots of detail?
The duotone mapping preserves tonal detail while remapping to your two chosen colors. High-detail photos often produce the most striking results. Processing happens entirely on your own server.
Can I batch-process images with the same duotone settings?
Yes, batch mode applies identical settings across multiple images. Running on your self-hosted instance means there are no per-image charges, making it practical for large content libraries.

More Adjustments tools

Adjust Colors

Brightness, contrast, exposure, saturation, temperature, sharpness, and effects

Learn more Sharpening

Adaptive, unsharp mask, and high-pass sharpening with presets

Learn more Replace & Invert Color

Replace specific colors or invert

Learn more Color Blindness Simulation

Simulate how images appear with color vision deficiency

Learn more

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