OpenGL2: The game is too bright and auto-exposure doesn't match the original

[zturtleman]

The OpenGL2 renderer is notably brighter when comparing screenshots between the opengl1 and OpenGL2 renderers.

For example in GIMP with subtractive blending the OpenGL2 image is still completely visible. It's not a few pixel values different over the whole image. It increases with brightness. If I remember correctly, the pixel values are around twice the value of opengl1 but due to non-linear sRGB colorspace it's not visibly twice as bright. I haven't review it again at this moment to provide images demonstrating this.

It's also probably hard to make it be the same brightness when auto-exposure is just arbitrarily changing it.