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Groups > comp.os.linux.misc > #14921

Re: pdf & O.C.R ?

From Unknown <dog@gmail.com>
Newsgroups comp.os.linux.misc
Subject Re: pdf & O.C.R ?
Date 2015-06-13 13:29 +0000
Organization A noiseless patient Spider
Message-ID <pan.2015.06.13.13.30.56@gmail.com> (permalink)
References <pan.2015.05.23.07.50.46@gmail.com> <bjj73c-fim.ln1@mail.binaryfoundry.ca> <mk1sam$r2l$1@dont-email.me>

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On Tue, 26 May 2015 13:26:46 +0000, Joe Beanfish wrote:

> On Sat, 23 May 2015 20:46:03 -0400, John-Paul Stewart wrote:
> 
>> On 23/05/15 03:49 AM, Unknown wrote:
>>> I'm confused and disturbed that xpdf of:
>>> http://www.inf.ethz.ch/personal/wirth/ProjectOberon/PO.Computer.pdf
>>>    is perfect to the pixel, with maximum magnification [400%], which
>>>    is expected, since it's computer-font generated, whereas:
>>> http://www.northernlaw.co.za/images/stories/files/actsandbills/COMPANY
%
>>> 20LAW%20ACT.pdf
>>>    shows blotchy and fibers as if it's a photo-of-a-paper-copy.
>>>
>>> And scanned copies of papers are apparently normal.
>>>
>>> BUT!! How is it that xpdf allows me to extract the text, via
>>> mouse-copy from COMPANY%20LAW%20ACT.pdf ?
>>> That would mean that the mouse-driver is doing O.C.R.   ?!
>> 
>> Why would you think the mouse driver is doing OCR?
>> 
>> A PDF file can contain both text and images.  It is common when
>> scanning paper documents to turn them into a so-called "searchable PDF"
>> that contains the scanned image of the page overlaid on top of the
>> (OCRed) text.  So what you see visually is the (possibly blurry)
>> picture, while what the mouse is copying (and pdftotext is extracting)
>> is the text that's hidden underneath.
>> 
>> Adobe's own Acrobat software can create such "searchable PDF" files.
>> I'm sure there are other tools, too.
> 
This is TOO-MUCH!!
You mean they send the original-keyed-in-pdftotextable, AND the graphical
image of the crumpled-paper-version <overlaid>. What's the aim of such
expensive deception?

> Yeah, It's kinda interesting when your workstation's bogged down and the
> pdf is big you might see the OCR text render first, then the image will
> render, covering it up. Or maybe that only happens in the browser when
> it's downloading and hasn't gotten to the image yet? Haven't seen it
> happen in a while.

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Thread

pdf & O.C.R ? Unknown <dog@gmail.com> - 2015-05-23 07:49 +0000
  Re: pdf & O.C.R ? Bob Tennent <BobT@cs.queensu.ca> - 2015-05-23 11:13 +0000
    Re: pdf & O.C.R ? Unknown <dog@gmail.com> - 2015-05-27 17:11 +0000
  Re: pdf & O.C.R ? John-Paul Stewart <jpstewart@sympatico.ca> - 2015-05-23 20:46 -0400
    Re: pdf & O.C.R ? Joe Beanfish <joebeanfish@nospam.duh> - 2015-05-26 13:26 +0000
      Re: pdf & O.C.R ? Unknown <dog@gmail.com> - 2015-06-13 13:29 +0000
        Re: pdf & O.C.R ? Robert Heller <heller@deepsoft.com> - 2015-06-13 12:52 -0500
    Re: pdf & O.C.R ? Unknown <dog@gmail.com> - 2015-05-27 17:10 +0000
      Re: pdf & O.C.R ? John-Paul Stewart <jpstewart@sympatico.ca> - 2015-05-29 20:31 -0400

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