[vidarh]

So interestingly that shows the Venus was IFF ILBM, which matches its origin as a demo image for Deluxe Paint rather than GraphiCraft.

The format for most of the others is described as "PLBM", which makes sense as P(L)BM is basically a cruder variation that'd allow dumping the screen/window content to the disc in planar format directly (native for all Amiga on-screen display prior to AGA or graphics cards) with minimal framing, while ILBM interleaves the bitplanes row by row (and can optionally use run-length encoding too), and so needs a bit more finesse.

It's kinda funny how they play up that the person who found this out "specializes in and is world-renowned for hacking and reverse engineering" - if you're remotely familiar with image file formats, it takes about 5 seconds of looking at these files in a hex editor to see that they're an IFF related format, and the chunk names are plain ASCII. I'm sure the person in smart - I'm not disputing that; but they're overplaying how much expertise is required for this.

Both ILBM and P(L)BM are formats you can write a basic decoder for in an hour or two - IFF contains chunk headers and length markers to let you extract each chunk, and you need the palette information and the bitplanes. ILBM also allows for basic run-length encoding. There's no complicated compression or anything else to make it hard.