Draft Ring

The image that comes to mind first is that of a World War II military intelligence person using a magnifying glass to study hard film photographs of enemy sites to detect potential targets or evaluate bombing damage. 
As technology progressed and CCD chips were developed which allowed images to be captured digitally, in black and white at first and then in color, it became possible to conceive of replacing the human with the magnifying glass with software.
The need became pressing when photo recon from aircraft and satellites produced miles of film that had to be analyzed for targets during the cold war.  The government invested heavily in target recognition software.