ASTC, ETC, and DXT are indeed efficient formats, especially when hardware support is available. In my case, the target devices are microcontrollers without GPUs and with very limited RAM. A software decoder for these formats would require more resources than are realistically available. That is why I am exploring a simpler format that can be implemented with minimal overhead and predictable performance, even on very constrained hardware.
Restricting PNG to a smaller subset is a reasonable idea, and I did consider it. The challenge is that even a limited PNG still requires handling deflate compression and integrity checks, which add complexity to the parser. On many classes of microcontrollers, that creates unnecessary overhead and dependencies. My goal is to design a format that can be fully described on a single page of documentation and implemented from scratch in just a few hours, while remaining flexible enough to extend in the future.
> simple to parse, memory-efficient, and easily implemented on constrained devices
have you considered (compressed) texture formats?
ASTC might very well meet your requirements, including performance on embedded hardware: https://en.wikipedia.org/wiki/Adaptive_scalable_texture_comp...
If not ATSC, also consider ETC and DXT.
ASTC, ETC, and DXT are indeed efficient formats, especially when hardware support is available. In my case, the target devices are microcontrollers without GPUs and with very limited RAM. A software decoder for these formats would require more resources than are realistically available. That is why I am exploring a simpler format that can be implemented with minimal overhead and predictable performance, even on very constrained hardware.
What about PNG but with a constrained encoder and decoder that only supports a minimal subset of the specification?
Restricting PNG to a smaller subset is a reasonable idea, and I did consider it. The challenge is that even a limited PNG still requires handling deflate compression and integrity checks, which add complexity to the parser. On many classes of microcontrollers, that creates unnecessary overhead and dependencies. My goal is to design a format that can be fully described on a single page of documentation and implemented from scratch in just a few hours, while remaining flexible enough to extend in the future.