I've measured decompression time of JBIG1 compressed page 0013 of 'flatland' on a STM32F303CC.
The source page was the following 800x600px image with an umcompressed size of 60kB.
The corresponding JBIG1 compressed image had a size of 7kB (11.6%) and was directly flashed to uC flash memory.
It took 768ms to decompress with the uC running @72MHz.
This may seem like a lot, but it will take around 1000-1500ms to refresh a 800x600 e-ink display in the first place.
With parallelising the three loops which load compressed image data from SD card, decompress and display it line by line, this should work out well, though.
Lessons learned:
- I'll need at least an ARM Cortex M3 running @72MHz with at least 8kB of RAM for the freeader hardware design, can't possibly go below if I want to use prerendered compressed image data and refresh the display under 1.5s.
- A will thus design for STM32F30[2,3], as it is pin-compatible with STM32F103, but features an embedded DFU bootloader.
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