I have not tried it, but what I read from Fontforge's documentation sounds a lot like it could do it. https://fontforge.org/docs/tutorial/editexample8.html htt

I have not tried it, but what I read from Fontforge's documentation sounds a lot like it could do it. https://fontforge.org/docs/tutorial/editexample8.html https://fontforge.org/docs/tutorial/editexample8.html Also Glyphs 3 seems to support it. "Each glyph contains a single image file. However, images can be provided for different pixel sizes.". It's been years since I last worked with Glyphs and back then it was more of a creation tool than an editor. I don't know if that has changed.