I have been working on creating a raster data layer using mid 1900s aerial images. The images are physical copies which I have scanned into my computer as JPEGs and individually geofenced to their precise, present-day locations. After georeferencing them I used the merge raster tool to create one raster data set of all the georeferenced images. This raster data set is made up of over 150 single images, which makes Arc very slow to load and do any work in. I have more images to georeference and add to my larger raster set so I need to find a way to compress the one I have so I don't have to wait 20 minutes in between each click of my mouse. I have looked into the compress raster tool as well as the build pyramids tool, but I am still unsure how to use them correctly to get the outcome I want. The raster data I am using is RGB three band. I would like my new raster data layer to function as a basemap overlay so I can compare the historic imagery to the current day ortho photos and lidar imagery layers.