I am scanning several rolls of B/W film and have noticed that a small number of shots have some sort of strange sharpening/edge detection behaviour which looks awful. The example below is from Ilford HP5 pushed 2 stops to iso 1600, scanned with an Epson V550 scanner, shown at 100%.
Settings are: B&W negative film, 16bit grayscale, 4800 dpi, unsharp mask set to medium (default), digital ICE on.
Note that this occurs on 1-2 shots per roll - most of the shots look great. I have tried adjusting/disabling the sharpness setting but the effect remains. What is causing this? Sharpening of a relatively large amount of grain at a relatively high resolution?