Hello,
when I see the K2 items in their category, the images show OK. When I click on one of the tags in the tag cloud (K2 tools module) the same articles are showing again but their images are blurry.

I have made sure that the "Item generic image width (in px). Used in user pages as well as tag, search & date listings." setting is set to 900px

Did you set that value before you added the images or after you added them?

Be aware that images are resized using the image-size parameter that is set on the moment you upload them. If you change that parameter afterwards the images are not re-resized, they stay as they were set before.

Ah, I see... I set the value after I added the images. I will upload again and see how it goes.

Check your override to see if there is an image hardcoded in the tag.php file.

If not, try reuploading the image.

Reuploading the image works. That being said, it's going to be hell to reupload all these images. Is there a shortcut?

There was a plugin in github but I cannot recollect its name.

Thanks anyway!

IS that the one?

github.com/rdeutz/rebuildK2imageCache

Yeap! I'm starring it so I won't lose it.
thanks