Evaluation of photographic enhancements of Landsat imagery

The photographic processing of color Landsat imagery was evaluated to determine the optimal enhancement techniques. Twenty-six images were examined to explore the effects of gamma values upon image interpretation in a subarctic environment. Gamma values were varied on the images of bands 4 through 7 prior to the creation of the color composites. This yielded color-composited images with various color balances. These images were evaluated in terms of visible geological features (drainage, lineaments, landforms, etc.) and landcover features (exposed rock and ground, coniferous forest, etc.). The results indicate that the most informative images are created by using gamma values of 2.0 for band 4, 1.0 for band 5, and 2.0 for band 6 or 7. Other photographic enhancements tend to enhance some features at the expense of others.