New answers tagged background-removal
You can do this with GIFsicle, using the following options: gifsicle -U --disposal=previous --transparent="#ffffff" -O2 anim.gif > anim_trans.gif where anim.gif and anim_trans.gif are the source and destination file names, and #ffffff is the hex code of the color you want to make transparent (here, pure white). (The important options here are -U / ...
This is very easy in Gimp. Just use the bucket tool to fill the background white, and export. Or if you want to go one stage further, then after that, use the select with the same colour tool, press delete (Making sure that your image has an alpha channel) add a new white layer, merge down and export as a jpg, png or whatever.
I use the pencil eraser in brush mode. Under the brush panel make sure the only boxes checked are Smoothing and Dual Brush, and it should show a mostly solid white brush preview. The brush with these settings should act just like "block mode" and erase everything under it. You probably already figured something out by now but oh well.
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