Evaluation of photographic enhancements of Landsat imagery

In this study, color Landsat images were photographically enhanced and then evaluated for information content. Twenty-six color images were enhanced by changing gamma values on the images of bands 4 through 7 prior to generation of the color composites. This results in color-composited images with various color balances. These images were evaluated and compared to standard color-composite images. The evaluation of the photographic enhancements was conducted as a geologic and land-cover photo-interpretative analysis of scene no. 5470–19560 acquired on 1 August 1976 of the Denali Highway area, Alaska. The commonly used gamma values of 1.0 for all bands utilized during image reproduction does not result in the most interpretable image. A more informative image can be derived by using gamma values of 2.0 for band 4, 1.0 for band 5, and 2.0 for band 6 or 7. The remaining photographic enhancements that were attempted are generally found to enhance certain geologic or land-cover features at the expense of others.