I stitched roughly 20 raster files together using the "Mosaic to New Raster" tool. Once these raster files were combined, though, the new output raster seemed to "darken"- the fine details of the grayscale images I am using became much less apparent when they were combined in to one file. The image quality is important because I am doing a cost-distance analysis, where the different shades are representative of elevation. For reference, please take a look at the images below.
Is there any likely reason for this change in picture quality? For reference, when using the Mosaic to New Raster tool I used a Pixel Type of 32-bit-Float, with one band, a mosaic operator of "Last", with a TIFF file type. I am also using ArcGIS version 10.1.