Color to Alpha

Color to Alpha is an extension specially made for Paint.net, the advanced graphic editing application. It gives you the possibility to extract any range of colors from a select image by tinkering with some intuitive settings. It can be tackled not only by skilled users, but also by beginners.

Simple integration with Paint.net

Getting this plugin up and running is a simple task, since there is no setup pack involved. Instead, you can copy the downloaded DLL file to the "Effects" directory in Paint.net, restart the utility if you have already launched it, as well as access the add-on from the "Effects" menu. It has a puzzle piece next to its entry, an icon that acts as an indicator for all external plugins.

Extract a color range and configure settings

The main window has a simple design and well-structured layout, enabling you to define the color range when it comes to the hue, saturation and brightness. This can be done by picking colors from the bars, or by entering their numbers in the dedicated boxes.
Any of these three properties can be disabled. Moreover, you can tweak the level of tolerance, feather and base opacity by moving some sliders, invert the alpha channel or leave it normal, as well as override the original alpha.
Worth mentioning is that you can preview the effects made to the picture in real time, so there's no need to apply changes to verify results and go back by undoing your actions or by deleting the last created layer.

Evaluation and conclusion

It integrated smoothly with the most recent version of Paint.net in our tests, without triggering it to hang, crash or show error dialogs. Although Color to Alpha hasn't been updated for a long time, it offers a simple solution for extracting color ranges from pictures.