I always used this, on rare times I need a layered image editor: https://en.wikipedia.org/wiki/Blend_modes https://en.wikipedia.org/wiki/Blend_modes Informativ

I always used this, on rare times I need a layered image editor: https://en.wikipedia.org/wiki/Blend_modes https://en.wikipedia.org/wiki/Blend_modes Informative article, but non-zoomable interface with tiny images on mobile is not great.