Or rather gimping ...
I have a paper document I want to scan and clean-up, unfortunately it's printed on government department (not very well bleached) paper, and was badly photo-copied at some point in its past, giving it a variably dithered grey background.
The document was probably 300 dpi laser printed originally and ought to be pure b/w, I've scanned it greyscale at 600 dpi
I tried various de-speckle and de-noise filters, they didn't help much.
I tried altering brightness/contrast, helps but can't get rid of all the dithered background without also getting rid of some of the text.
Similar for adjusting levels/curves.
A threshold conversion to b/w, with a 8 as the low point and 255 as the high point, isn't too bad, gets rid of the unwanted black dither pixels, but also gets rid of detail in edges of text leaving white "nibbled edge" dithering to the text
Best so far is to do a gaussian blur with a small radius, then apply a threshold conversion to b/w with about 50 as the low point and 255 as the high point, then re-scaling to 300 dpi marginally removes some blotchy edges.
Any "magic" technique I ought to try?