You could write your own filters in its custom language and save them, of course you could easily download existing filters from others and save them too. I don't remember if you could save composed filters, last time I used it was in 2007 and I was still in high school. I found my abandoned flickr profile, I really liked writing geometry filters [1]. The two spheres and the two spiral patterns were made using mathmap. Right now I can't find an easily installable version for Linux though. As far as I remember it could compile its filters to c then binary if gcc was available.

One other interesting property of mathmap: It didn't cache intermediate results between filters and handled images as if they were infinite and had infinite resolution. It works, because if you only care about one given pixel of the resulting image you can calculate the previous image pixels lazily. It allowed really convenient compositions, like composing a Mandelbrot-set generator and a zoom filter then zooming into the set indefinitely only adjusting the zoom filter.

I didn't try ImagePlay yet. Can you write your own filters in it or you can "only" compose from the existing filters? Writing your own filters was a killer feature of mathmap for me, especially for custom geometry filters.

[1] https://www.flickr.com/photos/10529466@N02/

Thanks so much@