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Heavy Speckling

Posted: 11 May 2017, 03:39
by Hasher
Hi all

Been scanning in microfilm but some have very heavy speckling. Beside cleaning the film beforehand does anyone have any advice for removing this post process. I have tried scan tailor and this has reduced it marginally .

Here is an example

Thanks for any help

Re: Heavy Speckling

Posted: 11 May 2017, 09:48
by cday
If you scan in grayscale (or colour) can the noise be reduced using a level adjustment?

Alternatively, does your scanner interface provide a way of adjusting the theshold at which the image is binarised?

Upload an example grayscale scan if you wish...

Re: Heavy Speckling

Posted: 02 Jun 2017, 02:46
by rkomar
I find that it helps to use an adaptive binarization algorithm in such cases. If your scanner doesn't provide such, scan the images in grayscale and apply that binarization using software afterwards.

Re: Heavy Speckling

Posted: 06 Jun 2017, 17:42
by b0bcat
The specimen tif supplied is b&w 2-colors and although 300dpi, I noticed is either insufficiently defined and/or too over-exposed to capture small typeface print.

If possible, the quickest route would seem to be re-scanning in greyscale at a suitable dpi, maybe say, 400, and adjusting the scanner optimally as suggested by others above, including as to brightness.