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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.

The is the original raster mosaic

This is the resultant raster after using the Mosaic to Raster tool

  • Did the actual cell values of the raster change after you ran the Mosaic tool, or just the appearance when displayed? – lambertj Jan 30 '18 at 4:18
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This is normal when mosaic multiple images into one mosaic image. The data did not change, what have changed is the appearance of the final mosaic image. The original data have different minimum and maximum elevation values, that is why some of them may look bright and others may look dark. However, when you combined all raster data together using Mosaic to New Raster, the output final image was stretch to its minimum and maximum pixel value based on the lowest elevation and highest elevation found within one of the individual elevation raster data.

To change the stretch of the output image elevation after mosaic, you can go the Layer Properties -> Symbology -> and change Stretch Type:

enter image description here

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