How is this a bad photoshop? It’s official art coloured with watercolours, markers or similar.
If it’s because of the hair colour: Takahashi Rumiko wasn’t too consistent with hair colours for various colour illustrations. The covers of volumes 3 and 11 of the Ranma 1/2 manga show Akane with brown hair while on the covers of volumes 12 and 14 she has black hair. The volume 34 cover shows Akane and Ranma-chan both with blue hair even though Ranma-chan usually has red hair. Some volume covers show her with black hair as well, though.
post #150451 is the volume 38 cover, which shows Akane with brown hair, similar to this post. post #915070 and post #915076 are official art as well and show Akane with black hair and Ranma-chan with pink hair.
Also I fail to see how this is “Low Quality” in general. Please elaborate.
Digging it up this is apparently the cover art for volume 22, but as you can see from the original it's been altered from the original character (Ranma-chan). Amazon JPN link and http://www.anymanga.com/ranma/022/
Yes, its some crazy western Akane fan that has been running around doing headswaps and bad photoshops of both official art as well as work done by other "fan artists" such as KJ. It's really awful. She/he never even asks the artists if she/he can do these edits nor does she/he even try to credit them on her/his deviantart page.