Results 1 to 3 of 3

Thread: OCR remarkably accurate yet some of the original text is completely unreadable

  1. #1

    Question OCR remarkably accurate yet some of the original text is completely unreadable

    http://trove.nla.gov.au/ndp/del/article/59720040

    The OCR quality of this article is superb, but the funny thing is that a large chunk of the original is illegible.

    I've attached a screen cap (prior to my correcting the text) where you can see that the start of each line is pretty much impossible to read. Fiddling with levels in photoshop I can see that some of that area is virtually blank - apart from some remnant pixels here and there the colour is exactly the same as the background.

    There must be further image processing done between the OCR process and web presentation? It's not just compression, it is almost completely blanking out some words.

    Check my corrections on the article ( http://trove.nla.gov.au/ndp/del/correction/59720040 ) to see how good the OCR was - many lines perfect, others with a few stray characters, a missing trailing hyphen, or other minor errors. I wouldn't have been able to correct this article otherwise, since I can't read many of the words.

    Is Trove able to "reprocess" the scan in any way to make it more legible?

    edit: attach doesn't seem to be working, here is the screen capture mentioned above. I've lined up the OCR and original article columns so you can compare them directly:

    Last edited by rowancrowe; 04-05-2011 at 12:24 AM.

  2. #2
    Staff Moderator mraadgev [NLA]'s Avatar
    Join Date
    Jul 2010
    Posts
    260
    Hi Rowan,

    The difference between the two is partly because the image displayed in Trove is different to the image that is sent for OCR - the OCR image is bitonal whereas the image in Trove is greyscale (although they are bitonal if there are any problems with the greyscale image). Although these images are created simultaneously they do undergo slightly different processing steps (which does include compression for delivery), which unfortunately sometimes results in the situation you have described above.

    Cheers
    Mark
    Mark Raadgever
    Trove Support
    National Library of Australia

  3. #3
    Prolific poster
    Join Date
    Feb 2011
    Posts
    166
    G'day Mark,

    It seems to me that the problem described here by Rowan is becoming increasingly common as more newspapers are added to Trove.

    Has there been a change in how the images are processed?

    I am guessing that the images presented on this site are processed in such a way so as to give a nice white background. Rowan's experiment with Photoshop would seem to support this as areas of the image seem to have been adjusted to pure white.

    But if in the process this image adjustment is causing many articles to become illegible then it seems very much a backward step. Surely having something readable is much more important than all articles having a pure white background.

    As Rowan points out it is almost impossible to read large chunks of such articles and equally impossible to correct them.



    Is this issue being addressed??


    Spearth

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •