When I load a jpeg and save it immediately after loading, no color shift is visible. If I do a to_rgb565 conversion, the impact on colors can be dramatic, for example here (on another image):
I tried it with and without cropping (referring to the previous forum thread where this post was originally found), to then realise that cropping did not matter, to_rgb565 conversion did. If you download any of the original images linked above and run the minimal working example, you will see the color shift. Here is the original image whose histogram is shown right above :
Can you post these issues on github so they can be tracked. This one and the jpeg decompress one? They both seem to stem from the same issue. I am free this weekend and can take a crake at fixing the hardware jpeg code.