[bitbank]

I just added the ability to decode progressive JPEG files (of any size) down to thunbnail images (1/8th sized) on MCUs with less than 32K of RAM. This is a unique feature because normally you would need enough RAM to hold the entire image as DCT blocks (and potentially the entire decoded image as well). I decode the first scan which normally contains the DC values and maybe a few extra coefficients. This allows generation of 1 pixel per DCT block, thus a 1/8th by 1/8th sized image without needing additional RAM. I can add support for full progressive decoding (even on constrained devices), but would needing additional funding to justify the effort.