Make transparent

Specially designed for Paint.net users, Make transparent is a lightweight plugin designed to make color ranges transparent, which especially comes in handy for customizing background colors.
It features an intuitive set of options that can be tackled with ease by all types of users, even those new to this advanced graphic editing tool.

Easy integration with Paint.net

There is no actual setup kit involved. Instead, you can copy the downloaded DLL file to the "Effects" directory of the application's installed location, and relaunch the tool if it was already running prior to this step.
The new extension can be accessed from the "Effects" menu. It can be easily spotted, since it's accompanied by a small icon that resembles the piece of a puzzle, which marks all external add-ons.

Set RGB channels to make colors transparent

All you have to do is pick a preferred color for the background from the color spectrum, or directly input the red, green and blue channels, if you know these values. This works for the entire image as well as separate selections.
Worth noting is that picture modifications can be previewed in real time. Therefore, it's not possible to commit them just to be able to inspect results and undo your action if you're not satisfied with the outcome. A button for resetting the RGB channels to their default values is available.

Evaluation and conclusion

Although it hasn't received updates for a long time, we haven't experienced any compatibility issues with the later edition of Paint.net in our tests. It didn't cause any stability issues to the graphic editing utility, such as hanging, crashing or prompting errors.
To wrap it up, Make transparent facilitates a straightforward solution for those interested in making color ranges transparent. It can be implemented into the extension pack of all Paint.net users.