Hi Harash,

Are you really using floatToRGB or it is not in use anywhere? This will never 
give you exact results because this will have quantization errors if you use 
normalized textures (so just GL_RGB). Try to use float textures directly. In 
your case GL_RGB32F_ARB (for three channels: min, max, and mean).

Another point which one has to check: when doing mipmapping if texture 
coordinates to grab from the previous level are correct. This might introduce 
errors either because wrong pixels are grabbed or interpolation is in between 
(so pixels are not grabbed at their center). I must admit it was a long time 
ago, that I have tested the shaders if they use correct pixel coordinates. It 
might happen that there is still a mistake. You can see it in the code, where 
there is a comment "(TODO check why -1 seems to be correct)". Because to the 
time I wrote the shader, I was pretty sure it should be +halfTexel and not 
-halfTexel there. However the results seems to be correct. The shader was 
original taken from my other application. 
I have to sit down and just to recheck all that mipmap stuff, but unfortunately 
I have not so much time for that :(



Cheers,
Art

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