Washed out bitmaps with Logarithmic Exposure Control?

Written by Jeff Patton on 06 September 2007.

If you're using logarithmic exposure control with mental ray and finding your texture bitmaps a bit washed out, then you may find this tip useful.

As the help files in 3dsmax state, you should use EITHER logarithmic exposure control OR an adjusted gamma, but not both together. But, when using the logarithmic exposure control I've found that my bitmap textures will often look washed out or lack contrast. As it turns out, the logarithmic exposure control is "acting" a bit like an adjusted gamma setting. Therefore, I realized that if I used an adjusted bitmap input gamma setting, I can get the contrast/color back in my bitmaps when using the logarithmic exposure control.

Here's some additional information to help clarify the method:

Logarithmic Exposure control with default gamma settings (click to enlarge)


Logarithmic Exposure control with an adjusted bitmap input gamma setting (click to enlarge)


As you can see in my controlled environment test scene, a bitmap input gamma setting of 1.6 seemed to work best on my monitors here. Keep in mind that you may need to use a different value for optimal results on your own monitor(s).

I'll provide the test scene I used above so you can quickly explore what value works best for you. You'll probably find a range between 1.4 and 1.8 works best, here's the test scene:
/images/stories/JeffPatton/Blog/Gamma_start.zip

IMPORTANT NOTE: I forgot to mention that due to a display issue, it's best to restart 3dsmax whenever you modify the gamma settings. If you don't there's a chance that it will not display the changes properly.

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