Gamma settings and classic EQ darkness are entirely different things. Setting the former was just how we, as newb humans/erudites, compensated for being nearly blind at night.
Furthermore, classic infrasion was not just "lesser ultravision", it added a orange hue mobs/players at a distance. You can see it on the left in the screen shot below (I'm sure there are better examples to be found). It was very helpful since light sources only illuminated your immediate surroundings.
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It's unfortunate, but the general consensus of our client-tinkerers seems to be that classic darkness isn't doable in the titanium client. Changing the gamma settings isn't going to replicate classic darkness any more then wearing sunglasses.