Photos App 'Set Desktop Picture' - degrades quality

[Sovon Halder]

If I set a photo as a background image from the Photos App, the quality is degraded.

For eg. a super high quality 5000x3000 13MB gradient image looks color banded when done in this way. But if it's set a background image from the file itself in Finder, it's perfect.

What am I doing wrong here?
[doublepost=1513539501][/doublepost]Proper

Color Banded

 

[Sovon Halder]

Update::

This happens only when I select the photo to be desktop picture from within the photos app. (Photos app > album > share >set desktop or System pref. > Desktop/screen share > Photos > album)

I spent some time over at #apple at freenode. Those guys couldn't also tell why the photos app is acting this way.

Anybody noticed this ?