I think many of you may not have noticed (I can be wrong, though) that I have an handy online tool to make a certain color in a picture to transparent. The tool works at least with Chrome and Fire Fox. It’s quite slow but works well on small pictures.
Below is a video of me using the tool:
My system is in Finnish, but I have added some translations to the video.
Do use it, if you have use of this kind of tool.