Solved! Go to Solution.
There are many different ways to translate or render a pixel value (e.g. RGB - Red, Green, Blue values as expressed in values ranging from 0-255) into a display "on screen" in ArcGIS. The reason for this is that it is often possible to "optimize" the display of an image by "stretching" out the pixels values across the entire range your computer screen can handle.
We are actually entering the field of color theory, gamuts and color proofing here also...
What seems to happen is that the rendering / stretch type is changed when adding the data to the Mosaic. Please note the stretch mechanisms DON'T affect the pixel values of the orginal image, they are merely for display in ArcGIS (unless you deliberately use some geoprocessing tool for images that writes out new data / pixel values based on a certain stretch).
You should be able to "restore" you image to the original display, by setting a similar "stretch" on the Mosaic, as on the original image. You can find the stretch options under the Symbology TAB of the layer properties. Choose RGB Composite / Stretch in the dialog, and start experimenting with the options.
For further reading, I really advice you to read the following Help pages:
Renderers used to display raster data
Raster rendering behavior
Improving the display of raster data and especially the section Enhancing the appearance of the raster data
I am having these same issues with my data and Marco's explanation has solved one of my problems. The other is that when you open the original raster you can see the pixel size. With the Mosaic Dataset those pixels have been smoothed out. Please see my attached images. Is there a way for you to have the Mosaic Dataset leave the pixel size the way it is in the original raster?
As for changing the stretch type and applying the gamma stretch, can you set this for the Mosaic Dataset in ArcCatalog so it doesn't need to be changed every time I open it in ArcMap?