Snarly's SceneFixer will also change those maps on selected models or whole scenes.

The default render gamma setting is 2.2.  Under such conditions, lighting becomes an issue;  you need fewer light sets to illuminate your scene.  And if you intend to use IDL, enclose your surroundings within a room enclosure or environmental skydome.  Without either, you will lose raytrace rays needlessly that would better serve providing naturally reflected light from your enviroment.  Render time will increase.