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GIMP, .pdf, and threshold

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GIMP, .pdf, and threshold m.roth@5-cent.us 11 Apr 14:40
  GIMP, .pdf, and threshold Kevin Payne 11 Apr 15:01
   GIMP, .pdf, and threshold m.roth@5-cent.us 11 Apr 15:23
  GIMP, .pdf, and threshold Tobias Jakobs 11 Apr 15:01
   GIMP, .pdf, and threshold m.roth@5-cent.us 11 Apr 15:23
m.roth@5-cent.us
2016-04-11 14:40:04 UTC (over 8 years ago)

GIMP, .pdf, and threshold

Hi, folks,

I'm running CentOS 6.7, and the most current GIMP for that, 2.6.9-8. A friend, half a continent away, is scanning parts of a number of old 'zines for me. From that, The originals were printed on colored paper....

I want to do OCR. On a couple of .pdfs, one I d/l from the 'Net, and one from a different scanner, I import it into GIMP as images (we're talking 16-20pp), and, page by page, push the contrast to max, cut the brightness to half or less of what it was, then pull up threshold, and the preview shows me black text on white, and saving it that way, tesseract works just fine.

Doing that with these scans, nada. No useful changes, and threshold does nothing.

Clues for the poor?

mark

Kevin Payne
2016-04-11 15:01:00 UTC (over 8 years ago)

GIMP, .pdf, and threshold

My initial guess would be that your image mode is Indexed.

Check Image>>Mode and make sure it is set to RGB after importing the images.

Kevin

From: gimp-user-list  on behalf of m.roth@5-cent.us 
Sent: 11 April 2016 15:40
To: gimp-user-list@gnome.org
Subject: [Gimp-user] GIMP, .pdf, and threshold

Hi, folks,

   I'm running CentOS 6.7, and the most current GIMP for that, 2.6.9-8. A
friend, half a continent away, is scanning parts of a number of old
'zines for me. From that, The originals were printed on colored
paper....

    I want to do OCR. On a couple of .pdfs, one I d/l from the 'Net, and
one from a different scanner, I import it into GIMP as images (we're
talking 16-20pp), and, page by page, push the contrast to max, cut the
brightness to half or less of what it was, then pull up threshold, and
the preview shows me black text on white, and saving it that way,
tesseract works just fine.

   Doing that with these scans, nada. No useful changes, and threshold
does nothing.

   Clues for the poor?

        mark
Tobias Jakobs
2016-04-11 15:01:47 UTC (over 8 years ago)

GIMP, .pdf, and threshold

Hi mark,

2016-04-11 16:40 GMT+02:00 :

Hi, folks,

I'm running CentOS 6.7, and the most current GIMP for that, 2.6.9-8.

Uff, that's an really old version...

Doing that with these scans, nada. No useful changes, and threshold does nothing.

Clues for the poor?

No, but could you perhaps upload on of the PDFs so that at least someone with an old Gimp 2.6 has the chance to reproduce the problem.

Regards, Tobias

m.roth@5-cent.us
2016-04-11 15:23:05 UTC (over 8 years ago)

GIMP, .pdf, and threshold

Hi, Tobias,

Tobias Jakobs wrote:

2016-04-11 16:40 GMT+02:00 :

I'm running CentOS 6.7, and the most current GIMP for that, 2.6.9-8.

Uff, that's an really old version...

It's what's current for CentOS 6 (and I *really* am putting off going to CentOS 7 as long as possible, I despise systemd, but that's another flamewar), and I'd rather just keep current. Btw, CentOS 6 == RHEL 6.

Doing that with these scans, nada. No useful changes, and threshold does nothing.

Clues for the poor?

No, but could you perhaps upload on of the PDFs so that at least someone with an old Gimp 2.6 has the chance to reproduce the problem.

a) I'm not used to mailing lists that allow that, as I think it was hundreds of k? over a meg?), and
b) I personally have an issue doing that - it's not just some random stuff, it's writing by my late wife in a fiction APA, that I finally got up off my butt to collect, so I can put into a publishable novel form. So, things like copyright (I would be the copyright holder).... Let me think about it - actually, it'd have to wait until this evening anyway, it's on my workstation at home, not here at work.

Here I was hoping it was seen before, here's a link to a thread....

mark

m.roth@5-cent.us
2016-04-11 15:23:53 UTC (over 8 years ago)

GIMP, .pdf, and threshold

Kevin Payne wrote:

My initial guess would be that your image mode is Indexed.

Check Image>>Mode and make sure it is set to RGB after importing the images.

I *think* it's RGB, but I'll doublecheck that. Thanks.

mark

Kevin

________________________________________ From: gimp-user-list on behalf of
m.roth@5-cent.us
Sent: 11 April 2016 15:40
To: gimp-user-list@gnome.org
Subject: [Gimp-user] GIMP, .pdf, and threshold

Hi, folks,

I'm running CentOS 6.7, and the most current GIMP for that, 2.6.9-8. A friend, half a continent away, is scanning parts of a number of old 'zines for me. From that, The originals were printed on colored paper....

I want to do OCR. On a couple of .pdfs, one I d/l from the 'Net, and one from a different scanner, I import it into GIMP as images (we're talking 16-20pp), and, page by page, push the contrast to max, cut the brightness to half or less of what it was, then pull up threshold, and the preview shows me black text on white, and saving it that way, tesseract works just fine.

Doing that with these scans, nada. No useful changes, and threshold does nothing.

Clues for the poor?

mark

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