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Thread: Convert light and coloured text to black

  1. #1
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    Default Convert light and coloured text to black

    Frequently I download PDF files that use light colour text. When I print them on my monochrome laser they are hardly readable. My Cups Printer Test Page shows everything is fine as far as the toner is concerned. Is there software that can change the colours to black and possibly increase the contrast as well?

    Thanks in advance.

  2. #2

    Default Re: Convert light and coloured text to black

    On 1/20/19 3:56 PM, ionmich wrote:
    >
    > Frequently I download PDF files that use light colour text. When I print
    > them on my monochrome laser they are hardly readable. My Cups Printer
    > Test Page shows everything is fine as far as the toner is concerned. Is
    > there software that can change the colours to black and possibly
    > increase the contrast as well?
    >
    > Thanks in advance.
    >
    >


    You should hav two settings, one for greyscale and one for black/white.
    Make sure you select the black/white setting.

    --
    Ken
    unix since 1986
    S.u.S.E.-openSUSE since 1998

  3. #3
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    Default Re: Convert light and coloured text to black

    Quote Originally Posted by kensch View Post
    On 1/20/19 3:56 PM, ionmich wrote:


    You should hav two settings, one for greyscale and one for black/white.
    Make sure you select the black/white setting.

    --
    Ken
    unix since 1986
    S.u.S.E.-openSUSE since 1998
    Thanks for responding.
    When I select the .pdf file it opens in Document Viewer. When I select Print it does not give me the option to change the printer settings.

  4. #4
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    Default Re: Convert light and coloured text to black

    If the PDF layout and formatting is not too complex for the LibreOffice importer, you can try importing the PDF into LibreOffice, then press ctrl+a (select all text) and make everything black-on-white.
    From this point on, you can do all kinds of tricks, making it multi-column, double-sided, print it with a more ergonomic reading font style+size etc. (I prefer to read larger quantities of text using a 13pt Georgia font, for example.)

    Saving the converted PDF as .odt or .odg, then renaming its ending from odg/odt to ZIP, you then may unpack (»unzip«) the document and get access to any images embedded in the original PDF in their original resolution. That way, you can even touch up those images to your liking in Gimp for an optimized grayscale or b/w printout. This works great for PowerPoint presentations too. There are even a few ink-saving tricks out there on the web, describing how you can rasterize large pictures for high-contrast yet ink-/toner-saving printing.

    Then there are many professional and often costly alternatives for programmers who need to integrate PDF processing into daily workflows. I've worked with PDFlib (about 400 Euro) professionally, mass-converting old TIFF scans into PDFs, adding/extracting barcodes/serial numbering/cut-/foldmarks, merging and separating b/w pages from CMYK pages, processing gigabytes daily, automated with Ruby scripts under SLES9 back then. I'm not sure free packages like GhostScript and friends can do all that yet. I remember an article in a Linux magazine detailing the database-driven creation of PDFs with some LibreOffice+Python automation, e.g. for web server usage (PDF receipts, invoices, data sheets and whatnot). So much possibilities.

    Nevertheless, if I want to do an ad-hoc quick-and-dirty PDF manipulation, I always try the LibreOffice angle first. Cheers!

  5. #5

    Default Re: Convert light and coloured text to black

    On 1/22/19 1:36 PM, ionmich wrote:
    >
    > kensch;2892112 Wrote:
    >> On 1/20/19 3:56 PM, ionmich wrote:
    >>
    >>
    >> You should hav two settings, one for greyscale and one for black/white.
    >> Make sure you select the black/white setting.
    >>
    >> --
    >> Ken
    >> unix since 1986
    >> S.u.S.E.-openSUSE since 1998

    >
    > Thanks for responding.
    > When I select the .pdf file it opens in Document Viewer. When I select
    > Print it does not give me the option to change the printer settings.
    >
    >


    Try opening the document in okular which should provide more control
    over the printer settings.

    --
    Ken
    unix since 1986
    S.u.S.E.-openSUSE since 1998

  6. #6
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    Default Re: Convert light and coloured text to black

    [QUOTE=unix111;2892260]If the PDF layout and formatting is not too complex for the LibreOffice importer, you can try importing the PDF into LibreOffice.../QUOTE]

    Thank you for the quick response and suggestion. I hardly ever use LibreOffice so it will take me some time to learn and use what you suggested. I will report back on my progress and success.

  7. #7
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    Default Re: Convert light and coloured text to black

    If the documents are not confidential you could use an on-line converter such as https://www.sejda.com/grayscale-pdf

    There is an option to choose text conversion as either grayscale or black.
    Regards, Paul

    Tumbleweed (Snapshot: 20190716) KDE Plasma 5
    Leap 15.0 KDE Plasma 5
    [Non-Tumbling Tumblweed (20150508) KDE 4 - Resurrected]

  8. #8
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    Default Re: Convert light and coloured text to black

    Thanks to all of you for suggestions.

    My LibreOffice 6.x does not offer an "Import" selection in the File menu, only an "Export". An Internet search for "linux libreoffice pdf to odt" produced only a solution for Ubuntu and version 3.x using a utility not in our repositories. The search also produces a link to ask.libreoffice.org which states "Libre Office Writer does not convert .pdf files to .odt."

    Nevertheless I found a bash utility at https://github.com/gutschke/pdf2odt/blob/master/pdf2odt which did convert. After fiddling it for quite a time I gave up and produced a .txt file which printed in black albeit unformatted. I edited the content with Leafpad and I now have a printed document that I can read. Online conversion was not tried as the document contains confidential information.

  9. #9
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    Default Re: Convert light and coloured text to black

    Using openSUSE’s default packages for LibreOffice 6.1.3.2, I just use »Open File« and select the PDF as I would with a WinWord/Excel/PowerPoint/RTF document — my apologies for my misleading description of »importing« PDFs.
    In Dolphin (nice KDE/Plasma5 file manager), I'm also able to right-click the PDF and then choose »Open With → LibreOffice Draw«. In Draw, you can select all the text, manually copy it over to a new LibreOffice text document (or anywhere else) and customize it for printing — or format it direcly in Draw, page by page, which I find a bit cumbersome.

    Thank you for mentioning pdf2odt, this seems like the way to go. I definitely will give that one a try. Cheers!

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