Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

Heavy Speckling

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Hasher
Posts: 75
Joined: 26 Sep 2009, 03:05

Heavy Speckling

Post by Hasher » 11 May 2017, 03:39

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
http://williams.aero/Pics/biton0001D06.tif

Thanks for any help
Paul

cday
Posts: 210
Joined: 19 Mar 2013, 14:55
Number of books owned: 0
Country: UK

Re: Heavy Speckling

Post by cday » 11 May 2017, 09:48

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...

rkomar
Posts: 86
Joined: 12 May 2013, 16:36
E-book readers owned: PRS-505, PocketBook 902, PRS-T1, PocketBook 623, PocketBook 840
Number of books owned: 3000
Country: Canada

Re: Heavy Speckling

Post by rkomar » 02 Jun 2017, 02:46

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.

b0bcat
Posts: 30
Joined: 30 Nov 2012, 21:37
Number of books owned: 0
Country: UK

Re: Heavy Speckling

Post by b0bcat » 06 Jun 2017, 17:42

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.

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