[Gimp-user] Graypoint and gamma

[Enno Fennema]

I fail to understand the relationship between Gamma and the value of the
Graypoint as shown in the Adjust Color Levels tool.

Leaving the input and output ranges from 0 to 255 and setting gamma =
2.0 I expected the midpoint triangle to move to about 64. Input 0.5 to
the power gamma is 0.25 (that is about 64 in 0 to 255 speak).

In fact the graypoint triangle is showing approx. 0.33 (or 85).

Would be grateful if someone could explain what is going on.

Thanks,
Enno