I have this same question. I have about 200 aerial photos that I need to scan and georeference. I was going to save them as jpgs with a dpi of 600. I tried tiff first, but the file sizes are so much bigger. Does it really matter what format the image is in? I checked out the border after scanning and it is not all one value (255). I was going to clip it in Photoshop first, but how much should be clipped? I thought that features in aerial photos became distorted as you get further away from the center. And with all the overlap, is it okay to clip a little more inside the border also? As Jeff said, it's better to do this correctly from the beginning.
I have a similar question, but now through ArcGIS Pro. We have just over 200 aerial photos. They have been scanned and georeferenced. The georeferenced images still have the marginalia items. I can clip each one since they represent 4 sections. Using the raster clip tool in ArcGIS Pro, the optional outputs are Create new layer or Save As which does not clearly specify the output format. My goal is to create a mosaic dataset with the clipped images. Anyone else converting old aerial images (pre-digital) and have some advice or recommendations?