What is the best ADF scanner?

Book scanning methods that involve taking books apart.

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cday
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Re: What is the best ADF scanner?

Post by cday »

Kjarrval wrote: 02 Apr 2023, 03:33 I've had great results with Brother ADS-2400N...

There can be some vertical lines ocurring which can be either grey or a white thin line which can in some cases be hard to detect (depends on how much one zooms). Since I care about those, I do need to check each page and rescan the faulty pages before I publish the results. These seem to be caused by dust particles (from the pages) and as a countermeasure it might be a good idea to vacuum the sheet feeding area of the scanner every 200-300 pages.
I did not mention earlier that I would think that it should be possible to devise a reasonably simple algorithm that could detect fine lines with no dark pixels on either side of them. As the unwanted pixels in a line would be aligned with the scan axis, an image might be checked one column at a time for too large a number of dark pixels. Alternatively, possibly each pixel might be checked in relation to its surrounding pixels, which might also potentially clean an image by removing any unwanted spots.

Such an algorithm might have a sensitivity control to allow for different scanning resolutions, and possibly a threshold control to allow for different line tints, if lines other than near-black can occur. Possibly some existing filters available in image editing software might provide some improvement. But, of course, prevention is always better than cure!
Kjarrval
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Re: What is the best ADF scanner?

Post by Kjarrval »

cday wrote: 10 Apr 2023, 13:14 I did not mention earlier that I would think that it should be possible to devise a reasonably simple algorithm that could detect fine lines with no dark pixels on either side of them. As the unwanted pixels in a line would be aligned with the scan axis, an image might be checked one column at a time for too large a number of dark pixels. Alternatively, possibly each pixel might be checked in relation to its surrounding pixels, which might also potentially clean an image by removing any unwanted spots.
For some reason, phpBB doesn't actually notify me when you respond to me (even though I configured it to do that).
Such a software would be awesome, even if it were only to notify me which pages could have such lines. The algorithm would need to take into account the use of lines in tables in the actual content and the use of black/white images, or it would have the potential for many false positives. If this discussion is an inspiration for someone to make such a software, there's also the problem of „a white line“ which blurs letter pixels in its path.
cday
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Re: What is the best ADF scanner?

Post by cday »

Kjarrval wrote: 12 Apr 2023, 04:00
cday wrote: 10 Apr 2023, 13:14 I did not mention earlier that I would think that it should be possible to devise a reasonably simple algorithm that could detect fine lines with no dark pixels on either side of them. As the unwanted pixels in a line would be aligned with the scan axis, an image might be checked one column at a time for too large a number of dark pixels. Alternatively, possibly each pixel might be checked in relation to its surrounding pixels, which might also potentially clean an image by removing any unwanted spots.
Such a software would be awesome, even if it were only to notify me which pages could have such lines. The algorithm would need to take into account the use of lines in tables in the actual content and the use of black/white images, or it would have the potential for many false positives. If this discussion is an inspiration for someone to make such a software, there's also the problem of „a white line“ which blurs letter pixels in its path.
My thinking was that a line in a sheet-fed scan from a spec of dust would normally be thin enough to be distinguished from page content such as a vertical line in a table. I am not sure how a light colour line such as a white line could arise?

Note that I am not a software designer, although long ago I did write a fair amount of assembler code for microprocessors, and that required conceiving algorithms for many varied needs.
Kjarrval
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Country: Iceland

Re: What is the best ADF scanner?

Post by Kjarrval »

cday wrote: 12 Apr 2023, 06:42 My thinking was that a line in a sheet-fed scan from a spec of dust would normally be thin enough to be distinguished from page content such as a vertical line in a table. I am not sure how a light colour line such as a white line could arise?

Note that I am not a software designer, although long ago I did write a fair amount of assembler code for microprocessors, and that required conceiving algorithms for many varied needs.
Not sure what causes the white line although it might be something white which gets stuck, or something else which causes each sensor to register a (near) maximum RGB number of each colour. This might be difficult to detect automatically but one proposal might be to detect an usual number of non-coloured pixels in a straight vertical line, except the margins themselves.
cday
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Re: What is the best ADF scanner?

Post by cday »

I would think that a white or light coloured line would likely be caused by something partly transparent, wouldn't it?

But from my limited experience with sheet feeder scanners, unwanted lines due to something on the scanner sensor are normally quite dark, which I think should normally make them reasonably easy for an algorithm to identify, provided they are thinner than any long vertical content on a page. I would think that there would be a number of possible alternative approaches to an algorithm.
Kjarrval
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Country: Iceland

Re: What is the best ADF scanner?

Post by Kjarrval »

cday wrote: 12 Apr 2023, 12:39 I would think that a white or light coloured line would likely be caused by something partly transparent, wouldn't it?

But from my limited experience with sheet feeder scanners, unwanted lines due to something on the scanner sensor are normally quite dark, which I think should normally make them reasonably easy for an algorithm to identify, provided they are thinner than any long vertical content on a page.
I'm not sure of the cause either since when I discover there is such a line, it's been solved by itself, i.e. the object has disappeared naturally or by vacuuming. I scanned everything and then I check to make any needed rescans. The file attachment shows an example of such a line.
Screenshot from 2023-04-12 17-22-10.png
Screenshot from 2023-04-12 17-22-10.png (276.39 KiB) Viewed 4880 times
cday
Posts: 440
Joined: 19 Mar 2013, 14:55
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Re: What is the best ADF scanner?

Post by cday »

I would think that other than an intermittent scanner hardware failure such as an unreliable internal contact, the the near-white line must have been due to something quite transparent on the sensor cover...

Good quality output that should compress well with Adobe Acrobat 'ClearScan' if that could be of any interest.
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