Invert colors of pdf file?

Discussion in 'The Tablet PC Life' started by spsuninja, Dec 6, 2013.

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  1. tsttm

    tsttm Pen Pal - Newbie

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    I'd like to find a simple (& preferably free) way to invert the colors of any pdf file- ie light text (white or yellow) on black background. I find I quickly get headaches if i'm reading black on white background.

    I want to find a way to "convert" the files..i do not want to ues the 'accesibility-> change color' option in adobe. The reason is: 1) it doesn't always work (sometimes text changes but not the background) 2) i want to use grahl pdf annotator to highlight/make notes & it does not have a feature to change the pdf colors (ie once in grahl, it's back to black on white so i need to convert the actual file).

    A solution I've tried so far, is to convert the pdf into image files using PDFill, then batch converting the images into negatives using fastone image viewer, then converting back to pdf using PDFill. It works well, except it's a little tedious & i lose the ability to search the pdf. I think adding an OCR step would enable me to search the pdf again, but i need learn a bit more about OCR & i'm concerned that after OCR, it won't be as reliable as the original pdf's search ability.

    Is there a way or program to do these steps at once? Anyone else have experience inverting/converting the colors of text of pdfs?

    thanks!
     
  2. ceejay

    ceejay Pen Pal - Newbie

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    I went looking for an answer because I like white text, too. Although, right now I'm at work so I can't totally try it.

    http://studio.imagemagick.org/pipermail/magick-users/2008-July/021502.html

    This is the first site I found on the subject, and it linked to the next site.

    http://imagemagick.org/Usage/formats/#vector
    Non-IM Alternatives
    If you really do need to do general convention between vector formats, the program UniConvertor, Sk1 Project (usually available as a standard linux package) and the VectorSection can be used to convert vector-to-vector without actually rasterizing the images.

    For general conversion of Postscript to other vector formats, look at "pstoedit", which is typically available in your systems extra package repositories. Also look at "epstopdf" which is part of the Comprehensive TeX Network (CTAN). TeX and LaTeX are UNIX documentation (book and scientific article) text processing system. It has lots of tools to do with Postscript and PDF formats.

    For SVG to PDF conversion, Wolfgang Hugemann <Auto@hugemann.de> suggests that the easiest vector to vector conversion was to display the SVG in a browser (Firefox) and the print it using a PDF printer driver. Though the "Uniconvertor" could be used too.


    I haven't hyper-analyzed these tips, but it seemed like it might be useful to you.

    I repeat--I haven't tried using these tools, but I want to help any way that I can.
     
  3. tsttm

    tsttm Pen Pal - Newbie

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    that quote is like a foreign language to me. I'll look over it again, but i'm still looking for something that's one or two clicks of a mouse solution.

    thanks for the post!
     
  4. Frank

    Frank Scribbler - Standard Member Senior Member

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    This post isn't really helpful.
    It just explains how to convert vectors from one format to a different format.

    But your PDF file uses text, vectors, images.

    I don't know a perfect solution, but one solution would be to write or find a software which inverts a specific display region. Similar to a magnifying tool, just without a magnification, only with a little pixel manipulation.

    I haven't searched for such a tool right now, but maybe you'll find such a software if you google a bit.
     
  5. tsttm

    tsttm Pen Pal - Newbie

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    i spent a whole afternoon googling yesterday. I'm surprised there isn't a simple solution, seems like a handful of people out there would like this as well.

    I did find a forum post mentioning pitstop pro as having this feature. But it costs money to buy that software.

    To be honest, i don't mind converting to images & back (i could let it run overnight to convert) but it's a shame to lose perfectly functioning searchability without doing OCR & the stuff i have is technical with graphs & figures..I'm not sure how good OCR software will be to decipher some of the stuff.

    Anyway, would love hear any further input.

    thanks!

    edit: i just came accross a pdf textbook that for some reason doesn't convert to images with pdfill. (when using accesibility in acrobat reader, the text is light but the page remains white). I'm not sure if it has to do with 'how' the pdf was created..but are there some pdf that will not convert to images? or should all pdf be convertible to something else? (be it images or word docs etc...?)
     
  6. that0n3guy

    that0n3guy Pen Pal - Newbie

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    First... check out this: http://www.genmay.com/showthread.php?t=779900
    (seems you can change background color with foxit pdf reader).

    WARNING - becareful when you are installing foxit reader... it likes to install a stupid 'toolbar' on your browser when you install it. So make sure you do a custom install and uncheck the toolbar.

    OR you could use gimp/photoshop to invert the pdf's.

    QUICK GIMP TUTORIAL FOR INVERTING PDF'S:

    -Download and install gimp: http://www.gimp.org/
    -Open the pdf with gimp: File -> open ->file.pdf
    An import from pdf screen will pop up. You can only import one page at a time (well.. you can do multiples, but it puts it in its own layer... ). I usually only up the resolution to about 150 or 200 pixels/inch.

    - Invert the colors: Colors -> Invert
    - Save the image as a tiff -> file -> save as

    done

    quick and dirty...
     
  7. Frank

    Frank Scribbler - Standard Member Senior Member

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    You should be able to convert any PDF page to an image file, maybe the program you use isn't the best.

    You could also use the Windows Magnifying tool, which allows you to invert half of your screen.
     
  8. tsttm

    tsttm Pen Pal - Newbie

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    Thanks. As for the foxit option, i believe that just changes the view in the reader, correct? Which is attainable in adobe reader anyway..as mentioned earlier i want to actually change the pdf file, so it's inverted in pdf annotator or on any other computer.

    For the photoshop/gimp option, is that not the same as what i was doing with regards to converting pdf to image, invert, then keep or change back to pdf? you're still losing the search functionality aren't you? That's my main concern.

    Ok, i may try a different converting tool then..i was hoping to stick to free options..maybe there's another one to try.

    Thanks for the magnifying tool. That's very helpful, if only there was a way to make it full screen..that would work.

    thanks for all the inputs.
     
  9. leaftye

    leaftye Old timer Super Moderator

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    What about changing the display options in Windows? I know there's a high visibility mode. I'd test it right now, but I'm in the process of doing OCR on a 500 page pdf at the moment.
     
  10. KenK

    KenK Pen Pal - Newbie

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    That just changes the Windows color scheme. It does work for web browsers and the like, but not graphical displays like PDF viewers.

    (Still, it's a useful command to keep in mind - it's activated by Alt-Shift-PrintScreen.)
     
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