1. Add both of the rasters into ArcMap, right click on each and select Properties > Symbology, click the Colormap, select Export Colormap and save the .clr file in the same location as the rasters with the same name as the raster it came from.2. Right click a file geodatabase and select New > Mosaic Dataset.3. Give the mosaic dataset a name and import the coordinate system from the rasters, and click OK.4. Right click the mosaic dataset and select Add Rasters, and in the input navigate to the rasters and select both of them, and click OK. If you leave Update Overviews unchecked proceed to step 5 and 6, if you checked it on, go to step 7.5. Right click on the Mosaic Dataset and Define Overviews.6. Right click on the mosaic dataset and Build Overviews.7. Right click on the Image and select Properties > Symbology and change Stretch to None.