What it does
DaltonLens combines desktop colour-identification tools with a browser simulator for colour-vision differences. Its desktop utility captures a screen region, identifies the colour under the pointer and highlights similar pixels in the captured image. The desktop code is open source under the BSD two-clause licence.
The desktop program runs from the system tray. Press Ctrl+Alt+Cmd/Win+Space to open the colour-information overlay, then drag over a region or press Space to select the window beneath the pointer. In the image viewer, click a pixel to highlight similar colours. Adaptive filtering helps handle softened edges in line plots. Holding Shift temporarily shows the original image.
The browser simulator accepts a sample or uploaded image and offers simulated red-green and blue-yellow colour-vision differences with an adjustable severity. It also exposes several different simulation methods. Click the image to compare with the original; large uploads are reduced to 800 pixels wide for responsiveness.
Simulation is approximate: individuals, monitors and lighting differ. The method explanations identify which approaches suit each simulated type instead of treating every filter as equally reliable.
The desktop source uses the BSD two-clause licence, permitting use and modification with notice requirements when redistributing it. Windows and Linux downloads are linked from releases, while macOS uses the App Store. The Linux build lists GTK3 and libappindicator3 dependencies; its stated test environment is Ubuntu 20.04.
Strengths
- Similar-colour highlighting helps follow individual lines through a chart.
- Both desktop and browser views provide a quick comparison with the original image.
Watch out for
- Browser uploads are reduced to 800 pixels wide when large.
- Simulations cannot reproduce every individual’s colour perception.
Best for
- People reading colour-coded plots and designers checking colour distinctions.
Sources
- DaltonLens | Software and technical posts about color blindness. (Oct 28, 2026)
- GitHub - DaltonLens/DaltonLens: Desktop utility to assist color blind people with different kind of real-time filters. (Oct 28, 2026)
- Online Color Blindness Simulator | DaltonLens (Oct 28, 2026)
- DaltonLens/LICENSE at master - DaltonLens/DaltonLens (Oct 28, 2026)