This is likely a very niche request, but perhaps there’s a genius here with the answer - or can point me to a better place to ask.
If I want it to look like a web page is loading an interlaced gif over an old modem connection, would there exist some tool to convert a given static image to an animated gif (preferably downsampled to 256 colours)?
You know, the one where it starts off as one giant coloured block which then gets progressively segmented into thinner lines with more detail as each interlaced line is received…
You can set a gif’s FPS yeah. There’s an app called gif.ski that lets you play around with this - add a folder full of PNGs to it and render a gif. The lowest the UI lets you select for FPS is 1 - I made one and stuck it here so you can see what that looks like.
You can use the same tool on the command line if you want a half frame per second rate, e.g.:
gifski --output interesting.gif --fps 0.5 --quality 70 *.png