Thumbnails Imagemagick & GD Problems

Hi,
i am running a Kirby installation on a Strato-Hosting Plan. When GD creates Thumbnails for images with a rather monotone background, it somehow adds a white grid in there which is hard to see but it is there:

http://possible.is/downdown/traumbuch-12-ff05015cf3aa115f31ad60adcff8435c.jpg

with Levels high:
http://possible.is/downdown/traumbuch-12-ff05015cf3aa115f31ad60adcff8435c-levels.jpg

When i try to switch to Imagemagick, i have another problem: all the resize conversions work, but as soon as i crop an image, the thumbs won’t be generated. I think the version number of Imagemagick is 6.7.9.

I am not sure how to troubleshoot this, so maybe someone has had experiences with that?

Thanks in advance,
Matthias

That looks like a color profile problem– are you saving your image as RGB without the common sRGB profile? This is a common error: You also get it on CMYK images run through GD. The lib simply can’t handly anything else than standard RGB.

Imagemagick handles profiles better but has it’s own problems.

I think the profile is not a problem here, i tested different quality levels and it seems to be a jpg glitch that happens on light gray backgrounds.
with a better quality level the images look better.

i still would like to switch to IM though, but it still doesn’t handle any croppings, which is weird, especially as only resize thumbnails are being created…

with IM i can have a proper preview in the panel, which i don’t get at the moment…

The grid looks like a regular JPG compression artifact – you simply need to set the quality of the thumb()function to a higher value. And sorry, I misinterpreted the second image as being the result, whereas you changed the levels yourself.

JPEGs lossy compression often adds artifacts on large single-color areas and soft gradients – depending on the quality. Some colors also are more problematic then others (red for example).