[ack_complete]

I would think that something like a bootloader would have fixed input and be able to rely on that, with signing if necessary, rather than the robustness of the decoder. Otherwise, someone who could replace the image would probably be able to replace the code as well.

Without Deflate compression, PNG would have no compression at all, as the predictor mechanism gives no savings on its own. TARGA with RLE would be a better choice than PNG-0.

[Retr0id]

I thought that too, but then the "LogoFAIL" vulnerabilities came out.[1]

It's possible to define a subset of the deflate bitstream that only does simple RLE compression, and I've done so: https://gist.github.com/DavidBuchanan314/b223bce114ec715a66f...

But, for logo/icon sized bitmaps, you can generally get away without needing compression at all. A 128x128 1bpc image is a mere 2KB.

[1] discussed here https://news.ycombinator.com/item?id=38515571