Check a Chart's Colorblind Readability

Import a chart or data visualization screenshot: the tool simulates how it renders for the main types of color vision deficiency and gives you practical advice to improve its accessibility.

Example:
Drag and drop an image here, or click to browse (25 MB max).

How it works

The tool applies the same colorblind simulation matrices to your image pixels as our general image simulator, but in a context designed for charts: in addition to the three simulations (protanopia, deuteranopia, tritanopia), it counts the number of distinct colors used in the image and provides general accessible-design recommendations.

Why are red and green especially problematic in charts?

The two most common forms of color blindness (protanopia and deuteranopia) make red and green difficult to distinguish from each other, yet these have historically been the colors most used to represent “positive” and “negative” in financial or performance-tracking charts.

What if my simulations show that two series become indistinguishable?

Change your chart tool's color palette for hues with more contrast in brightness (not just hue), or add visual redundancy: different fill patterns, icons, or data labels directly on the chart.

100% local processing: simulations and color analysis happen entirely in your browser—your image is never sent to a server.