Can you double check that the correct image size is being used?
Did you reupload the image?
As I have already told you, PHP image processing and GD in particular has some flaws (it is a 3rd party library we are not responsible for that library).

If you are uploading logos where no compression should be made or images that png format is preferred, then you can tweak your template to show an extrafield image instead of the value of an image. You can use this code as a starting point -> github.com/kricore/Advanced-templating-with-K2/blob/master/_inc/cheatsheet.php#L77-L82

Hi

I have the same issue and the cause isn't about PHP GD library.
The problem is : when you set width in K2 image tab, K2 insert just CSS command and image is smaller than it.

For example I set 2000px for full style but in frontend k2 makes 850px image + (width:2000px css) and result is bad experience for user. Even I uploaded again high quality image in article.

The interesting point is I don't even have 850px value in k2 image tab setting!
Maybe it's a bug.

I never found a solution!

Since 2 years I'm on WordPress now.
And it is so better, and you can compress with a lot of parameters.


Regard.