Create small high-quality GIF/APNG from a bunch of PNGs

I have 50 PNGs (like [those ones here](https://github.com/nschloe/optimesh/raw/gh-pages/examples/pngs.zip)) and I would like to create a GIF (or APNG) animation from it that approximately retains the quality and is small. What I'm doing so far is to rescale and throw optipng at them: for file in step*.png; do \ convert -trim -resize 200x200 $$file png8:$$file; \ optipng -quiet $$file; \ done After this, the size of the individual PNGs is about 30KB. (Perhaps more can be tuned here.) Then it's conversion time: $ apngasm out.png step*.png The output file, however, still clocks in at a whopping 1.3 MB. Any idea of how to improve this?