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Willus.com's K2pdfopt
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22 Mar 2014

(Windows, Linux, OSX)

(GUIs; Native Kindle PDF Viewer)

(with videos)






Arch Linux


Linux Install

Mac Install
K2pdfopt optimizes PDF/DJVU files for mobile e-readers (e.g. the Kindle) and smartphones. It works well on multi-column PDF/DJVU files and can re-flow text even on scanned PDF files. It can generate native or bitmapped PDF output, with an optional OCR layer. The MS Windows version has an integrated GUI. K2pdfopt is open source. Here's a quick example (click on the images below to get the PDF files):

(8.5 x 11 PDF or DJVU file)
   . . . INTO THIS.

(6-inch reader screen)
     . . . OR THIS.

(4-inch smartphone screen)

New (v2.0) MS Windows integrated GUI front-end

Unsolicited comments from k2pdfopt users (refresh the page to change the comments):

         "Thank you so much for k2pdf - it has just, very beautifully, turned a syntax tree-ridden pdf into something my new Sony Reader will actually be able to display in a sensible way. I was about to return the thing to the store because I couldn't find a way to read full-sized pdfs on a 6 inch screen. :)" -- Jan 22, 2012         

         "Thank you for all your efforts with k2pdfopt, it's enabling me to make some real use of my "nook Simple Touch" to read technical manuals etc." -- October 16, 2012         

30 Mar 2014    I've added a new PDF Conversion Tips page to my web site, and also updated my examples below.
22 Mar 2014    K2pdfopt v2.15 released. This is a bug fix version which primarily fixes some memory leaks. See the details in k2pdfopt version history.
31 Dec 2013    K2pdfopt v2.14 released. This is a mostly cosmetic change to some of the source files, but it does fix an incorrect Win32 build from v2.13. Thanks to Dirk Thierbach for some of the source modifications. See the details in k2pdfopt version history.
30 Dec 2013    K2pdfopt v2.13 released. The crop box option (-cbox) is more powerful now, KOReader patches have been applied, and other minor bug fixes and enhancements have been incorporated. See the details in k2pdfopt version history.
21 Dec 2013    I have modified my download script so that it should correctly implement HTTP_RANGE byte ranges to support re-startable downloads. I don't know how to test this, though.
30 Nov 2013    K2pdfopt v2.12 released. Another minor bug fix for the Windows versions only. See the details in k2pdfopt version history.
30 Nov 2013    I revised some of the help pages today, adding more screen shots of the Windows GUI and a new video.
28 Nov 2013    K2pdfopt v2.11 released. This is a minor bug fix for the MS Windows GUI only. See the details in k2pdfopt version history.
23 Nov 2013    K2pdfopt v2.10 released. In v2.10, k2pdfopt now preserves the PDF bookmarks / outline tree. It also allows you to supply your own set of bookmarks. There is also a command-line crop-box option which gives k2pdfopt similar capability to Briss, for example--allowing the user to select arbitrary crop boxes from even and odd pages. Various bug fixes have also been implemented. See the full details in k2pdfopt version history.
[... more news]

K2pdfopt (Kindle 2 PDF Optimizer) is a stand-alone program which optimizes the format of PDF (or DJVU) files for viewing on small (e.g. 6-inch) mobile reader and smartphone screens such as the Kindle's. The output from k2pdfopt is a new (optimized) PDF file. K2pdfopt is meant for text-based files on a white background which may also have graphics or figures, and it works equally well on native and/or scanned or bitmapped PDF or DJVU files. It is fully automated and can batch-process PDF/DJVU files. K2pdfopt works by converting each page of the PDF/DJVU file to a bitmap and then scanning the bitmap for viewable areas (rectangular regions) and cutting and cropping these regions and assembling them into multiple smaller pages without excess margins so that the viewing region is maximized. Making use of this method, k2pdfopt can re-flow text lines, even on scanned documents (see the Winnie the Pooh example below). You can see another example of how k2pdfopt works on this help page.

As of v1.50, k2pdfopt will also embed OCR text into the PDF so that text can be searched and highlighted, and v1.60 can create output files with the native PDF instructions from the source file (if the source file is PDF). Any kind of PDF/DJVU file (best if it has a primarily white background) can be converted. K2pdfopt works especially well on two-column or multi-column PDF/DJVU files such as IEEE and other technical journal articles (see examples below--it auto-detects two-column regions on the page), but even single-column files will often be significantly improved and much easier to read (see examples). K2pdfopt has the advantage over other PDF converters in that it fully preserves the rendered PDF fonts and graphics from the original file, unlike programs that convert the PDF to an e-book format. Also, because k2pdfopt is completely independent of language or fonts, it will work equally well on documents in any language.

   No install is required and no extra files or packages are necessary to run k2pdfopt. Just drag and drop your PDF/DJVU file icon onto the k2pdfopt icon to convert it. You will be prompted for conversion options (as of v1.16). Press <Enter> to convert the file using the default settings. A new PDF file with _k2opt at the end of the name will be created. The output file is optimized for viewing on Kindles and other mobile readers with 6-inch screens (if the settings are not customized). Or drop a folder full of PDF/DJVU files onto the k2pdfopt icon to batch process. You can even drop a folder full of bitmap images to have them converted into a single PDF as if they were pages of a PDF file.

See my k2pdfopt help page for more detailed help.

Note that if you have a Kindle 2, it must have the latest firmware that allows it to view native PDF files.

EXAMPLES (click on images to get PDF file)
Example Type Original
for Kindle

(default settings)
for Smartphone

(-odpi 250)
(must use -col 4)

(must use -col 4)
Scanned pages
Two-column #2:

    9-5-13    JonTedesco.net
    1-28-13    Intelligent Rumblings
    1-7-13    Net Buffalo (In Japanese)
    12-1-12    blog.trufanov.com (In Russian)
    11-26-12    Zitimata (In Greek)
    11-4-12    abstractmodem.com
    9-20-12    ozgurlukicin.org (in Turkish)
    6-27-12    equiscentrico.com (in Spanish)
    6-26-12    ketabkhan.info (in Persian)
    1-4-12    TechLogon.com
    12-6-11    Herouxapps.com
    12-2-11    note1day.com (in Chinese)
    11-9-11    Świat Czytników (in Polish)
    11-5-11    tivasyk.info (in Ukrainian)
    11-1-11    WMLCloud.com
    10-31-11    linospapa.blogspot.com (in Greek)
    10-27-11    Steve Gibson's Security Now #324
    10-21-11    addictivetips.com
    10-12-11    Paper4Kindle (in Chinese)
    10-7-11    mexxbooks.com (in German)
    10-7-11    the-ebook.org forums (In Russian)
    (varies)    mobileread.com forums
    9-7-11    habrahabr.ru (in Russian)
    8-5-11    reddit.com/r/kindle
    8-4-11    steepbend.ru (in Russian)
    8-3-11    ssnjara.wordpress.com (in Croatian)
    8-3-11    xenicom.org (in Italian)
    8-2-11    howtogeek.com (note comments from "willus")
    7-30-11    artiss.co.uk
    7-30-11    ideasfor.info (in Russian)
    7-29-11    vyazovoi.blogspot.com (in Russian)
    7-27-11    guidingtech.com (note comments from "willus")
    7-27-11    tinhte.vn (in Vietnamese)
    7-23-11    triple-click.net (in Greek)
    7-23-11    computerbooks.moole.ru (in Russian)
    7-22-11    blog.rgub.ru (in Russian)
    7-22-11    aldus2006.typepad.fr (in French)
    7-22-11    korben.info (in French)
    7-21-11    expertoeninternet.com (in Spanish)
    7-21-11    eboocek.cz (in Czech)
    7-21-11    lifehacker.ru (in Russian)
    7-20-11    redferret.net
    7-19-11    freewaregenius.com (full review)

See my page on PDF Conversion Tips.

This is my plug for Krzysztof Kowalczyk's Sumatra PDF reader: a small, efficient, yet feature-rich open-source PDF reader that does everything I want. Sumatra also displays several file types other than PDF, including XPS, DJVU, CBZ, CBR, and PS/EPS (PS/EPS requires Ghostscript), EPUB, and MOBI. It is a refreshing alternative to Adobe's bloatware. I highly recommend it.

This page last modified
Tuesday, 01-Apr-2014 06:46:02 MDT