Items in item frames are darkened when rotated.

Right clicking an item frame which contains an item in order to flip it, flips the item, but shows a darkened version of the texture.

I right clicked the item frame and the flipped texture was darker than normal.

Steps to Reproduce:
1. Put item in frame
2. Right click item

Flipping the item all the way around to what it was before, makes it lighter again.
It will not darken blocks put in the frame and flipped.