[mkl]

Yes you can. I've done a lot of photo editing in Krita. My cameras output 12-bit raw images, which for a long time GIMP could only work with by truncating to 8-bit. Krita has been able to work with higher bit depths for a long time.

People do photo editing in Krita just like people do painting in Photoshop. Both tools can do both, as can GIMP, it's just that most of Krita's new features of the last few years have been focused on painting.