robert

@horst: I’m sorry if my comment sounded like an advice or a complete solution, which is definitely wrong. I just wanted to say that it worked for me and it removed the posterization in my images. I got your link on the other thread with the explanation, I obviously missed it before – thanks for the info!

Hi everyone, I had a similar problem with posterization/banding in darker image areas and found out the same workaround as chrizz (commenting out the gamma correction lines). I’m just guessing, but is it possible that the first gamma correction creates tonal gaps in those areas which can’t be fully reproduced afterwards? Btw: here is a new post which seems to describe the same problem: http://processwire.com/talk/topic/5889-image-quality-problem-on-resize/

Hi humanafterall, I had a similar problem with the resizing function and posterization in dark image areas, my workaround was to comment out the gamma correction in the Imagesizer.php (lines 247 & 387). I’m not sure what that function is good for, but now everything looks good. There is a similar discussion going on over here.