Quote from Wordpress' image editor:

The thumbnail image can be cropped differently. For example it can be square or contain only a portion of the original image to showcase it better. Here you can select whether to apply changes to all image sizes or make the thumbnail different.

This is exactly what I'd like to do, except for the fact that I don't want Wordpress to scale it down to 150x150 pixels (or another predefined resolution). I'd just like to display a cropped (and therefore smaller) version of the picture which is then linked to the (uncropped) original. I also tried to set the thumbnails' width and height to 0 in the preferences. Then, however, I don't even get the chance to assign a cropped version as thumbnail in the editor.

Could you tell me how to achieve that? Or isn't it possible at all?