ColorAid v0.9.3-beta


ColorAid is a color picker and highlighter, which can be especially useful for the color blind. It lets you point a color on an image (either loaded from file or captured from the screen), and highlights all the areas of the image having that color (or a similar one, according to given tolerances). Ideal for those nightmarish colored pie charts we sometimes struggle against.

Confused? A video is worth a thousand words:

(If you see nothing or just a still image, watch the video on Dailymotion.)


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Microsoft Windows XP/7/8
Installer | ZIP package
If you are not sure, please download the installer.

Builds for Mac OS X and Linux packages are coming soon.

ColorAid is released under the GPLv3 license. You can browse the source code from here.
To build the source under Linux, install Qt development packages and then run qmake; make.


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At first glance ColorAid’s interface may look intimidating, but using it is actually very simple once you master a few basics.

The idea is that as you move the mouse over a certain point of the image, the areas of the image having a similar color start blinking all together.

When talking about colors, the concept of similarity is far from being unambiguous, though. ColorAid relies on the following concepts: hue, saturation, and lightness. The web is full of excellent explanations about the HSL color space, and if you are interested in the math behind it you may read this Wikipedia article, but basically the hue is the tint (e.g. red, yellow, blue, etc...), saturation indicates how much different the color is from gray, and lightness... well I think it is self-explanatory.

Hue ranges from 0 to 359, whereas saturation and lightness range from 0 to 255. It is important to know that hue values lie on a circle, meaning that 2 and 357 are actually very close. Moreover, hue has no meaning for shades of gray (including white and black).

You can move the three sliders labeled hue tolerance, saturation tolerance, and lightness tolerance to adjust ColorAid’s sensitivity. For example, if you set saturation tolerance to ±50, lightness tolerance to ±25 and hue tolerance to ±30, and you move the mouse over a pixel having hue 10, saturation 20, lightness 250, you will match all the pixels having hue from 339 to 40 (remember: hue values lie on a circle), saturation from 0 to 70, and lightness from 225 to 255 (remember: saturation and lightness are in the range 0-255).

Shades of gray are treated as a special case: only other grayscale pixels are highlighted, that are within the provided lightness tolerance (saturation is always 0 for shades of gray, and hue has no meaning).

Once you have set the tolerances, you can play with the sliders labeled flashing speed and flashing color to make blinking slower/faster or darker/brighter.

Example images

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For bug reports, comments, and suggestions, feel free to contact me at


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Developing ColorAid takes time and efforts. Consider making a small donation for supporting the project.