Definitely looked like a hardware problem: Either a dead pixel in the CCD array or somthing preventing takeup. What I find useful for troubleshooting, calibration:
Scan a light gray target (plain paper, ...) at the highest optical resolution with all processing turned off. Descreening is useful for magazines, but it tends to mush over scanning issues. A high resolution scan like that should show issues with the hardware, dirt, and color casts.
I am usually careful about keeping the glass plate of my magazine scanner clean. If it is dirty I clean it with a little bit of cleaning alcohol and wipe it with a microfiber cloth.
The wiping is needed at least once for every scanning session since these old magazines leave small dust particles behind. They are easy to spot when you take an LED flashlight and point it at a shallow angle at the glass.
|