[MC-108960] Signs are lighter/darker due to their rotation

Standings Signs in the rotations 11, 12, 13, 14, 3, 4, 5 and 6 have the texture of the sign, where the text appears, darker.
This effect occurs from any angle.
NOTE: It seems that the displayed text is lighter, which is NOT the case. I analyzed the colors and they are exactly the same.

Testing was done in a DEFAULT world generated with the related snapshot.

For a more detailed look, watch: https://youtu.be/k3b7onVxvQQ

Environment

Windows 10 Anniversary Update
Java 1.8.0_101
PC: - i7 5820k @ 4Ghz - GTX980 (driver: 372.90) - 16GB RAM

Linked issues

duplicates 1

MC-33304 Sign Colors Fading (NOT vanishing!) when facing north or south Closed

Comments 2

migrated 2016-10-20T13:35:12Z

This affects all blocks and make the world seem more correct.

migrated 2016-10-20T14:46:52Z

It seems strange that the dimming stays in place no matter from which angle you look at it, which is not the case with other blocks.