DON'S FREEWARE CORNER - APR 2016
USING K2PDFOPT AND CALIBRE TO CONVERT A PDF TO
EPUB FOR MOBILE DEVICES
©2016 Donald R. Snow
This page was last updated 2016-06-13.
These Freeware Corner notes are published in
TAGGology, our Utah Valley Technology and
Genealogy Group (UVTAGG) monthly newsletter.
They are also posted on my Freeware Corner
Notes page on http://uvtagg.org/classes/dons/dons-classes.html
where you can just click on the links and there
may be corrections or updates after the printed
version.
PDF'S AND EPUB'S
PDF (Portable Document Format) is the format that
Adobe developed and which has been accepted by
many organizations as a standard for documents,
since it appears exactly the same on any computer
and in any operating system. There are
several varieties of PDF, but all have the image
layer which is just a picture of the page.
This may include text or photos or anything
else. To be searchable, besides the image
layer, there has to be a text layer which shows
that the various symbols on the image represent
words. This text layer is formed by OCR'ing
(Optical Character Recognition) the image layer
and is superimposed over the image layer so it
shows where the words are on the page. These
can be in English or French or other
language. Because the image layer is only a
picture of text and not text itself, the font or
font size can't be changed on a PDF and the only
way to make it larger is by enlarging the entire
page. This may make it so you have to scroll
to see it all on small screen. EPUB and
other mobile device formats are different, since
they have the text itself in them, so it is
possible to change the font and font size without
changing the page size. Because of this
people have developed ways to convert PDF's into
EPUB's to read on small-screen mobile devices.
The conversion may require that one PDF
page goes into 3 or 4 EPUB pages. One
method of conversions is to first change the PDF
into html (computer jargon for hypertext markup language)
and then change that to EPUB. This
requires OCR'ing the document first, noting the
paragraphs, lines, tables, etc., converting that
to html, and then converting the html to EPUB.
Because of the complexity of PDF's,
CALIBRE doesn't do a very good job of converting
directly from PDF to EPUB and the CALIBRE Manual
even states that PDF is the absolute worst format
to start with for such conversion. A comment
I came across on a forum about how to do this
conversion suggested that you can improve the
final EPUB result from CALIBRE by first converting
the PDF to a different format of PDF by using the
freeware program K2PDFOPT before running that in
CALIBRE to convert to EPUB. That's what this
Freeware Corner article is about.
K2PDFOPT -- available from http://www.willus.com/k2pdfopt/download/
This free program helps make PDF and DJVU files
more readable on small devices, e.g. smartphones
and tablets, but they are still PDF or DJVU files.
DJVU is another document format type, but
not used as widely as PDF. With this program
you can crop the pages, set the margins to be
narrow or even 0, and set many other preferences
to make it more readable, but it is still a
PDF. The statement was made that this new
PDF converts in CALIBRE to a better EPUB than the
original PDF and my quick experiments seem to
verify that.
USING K2PDFOPT
There is an 8-minute YouTube tutorial about
K2PDFOPT at https://www.youtube.com/watch?v=oCkJ3hLuT3E
and there are Helps on the main webpage. To
use K2PDFOPT download the version you need from
the webpage, e.g. my computer needed the Windows
7x64-bit version. It downloads as the
executable file, i.e. the .exe file, and doesn't
need to be installed on your computer. After
downloading I right-clicked on it to make an icon
on my desktop so I can run it without looking for
it every time. The program opens with a
window where you add the PDF files to convert and
there are lists of settings you can change.
You can add one or more PDF's at a time.
Here are some of the settings and what I
used.
Where to store the final file?
How much to crop each page? (I said, don't
crop at all.)
What margins to use in the final file? (I
left these set to 0-inch margins all around each
page.)
Maximum number of columns per page? (I left
this at 1, even though the book PDF I worked on
had two columns per page.)
What final device format do you want, e.g. several
Kindle versions, several Nook versions, Kobo, or
Nexus? (The YouTube tutorial says that
all it really needs to know about your mobile
device are the dimensions of its viewing screen.)
The settings can be saved with a name so you can
click and bring those all in at once next time.
There is a Preview panel where you can select a
page from the old PDF and see what its conversion
will look like, but I haven't used that.
With everything set click Convert All Files
and it starts through the old PDF's, first
examining their properties and then converting
them. The example I used was a 197-page book
I had downloaded in PDF format from HeritageQuest
Online a couple of years ago. The conversion
seemed to take about 1 second per PDF page.
It showed me how many new PDF pages each old
PDF page had gone into. In my example I had
set it to have only one column and this caused
each original PDF page to go in one new PDF page,
even though most pages had two columns. The
entire 197-page PDF book took about 3-4 minutes to
convert. It saved the new PDF file where I
had told it to and added "k2pdfopt" at the end of
the name, so it didn't overwrite my original PDF
file in the same folder. There are
additional things that K2PDFOPT can do and further
information about it in the tutorials.
USING
CALIBRE TO CONVERT TO EPUB FORMAT
CALIBRE was
discussed in my Freeware Corner column last
month (Mar 2016) and there is
a 10-minute CALIBRE tutorial at https://calibre-ebook.com/demo
. A short summary of CALIBRE is that
it is an open source program, and hence
free, available from https://calibre-ebook.com/
, that is an ebook library cataloger,
manager, reader, converter, viewer, and
editor, and works with many different ebook
formats. It will also convert ebook
files between many different formats and
also has features to go out on the Internet
to find other ebooks you want. It is
cross-platform so there are versions for
Windows, OS, and Linux. To transfer
ebooks in CALIBRE onto your mobile device
you connect the mobile device to your
computer and CALIBRE detects the connection
in a few seconds. Then highlight the
ebook you want to transfer, click Send To
Device, and it is transferred. If it
isn't already in the format needed by that
device, CALIBRE will convert it to the
needed format as it is transfered and it
will then be on your mobile device ready to
be read.
To use
CALIBRE to convert the new K2PDFOPT PDF
click the Add button (top left) on CALIBRE
and tell it where to find the new PDF.
It brings it in, recognizing and
keeping track of its properties. After
a few seconds you see it listed in your
CALIBRE Library list. If you click on
it there or on the word PDF in its property
list on the right-hand side, it shows it in
the PDF reader you have designated as the
default on your computer. To convert
it to EPUB format highlight it and click on
the Convert Books button at the top and set
the settings the way you want. It will
start converting the new PDF and when
finished in a few seconds you will see EPUB
added to the format types in the properties
for that title. Clicking on EPUB there
will now open it in the CALIBRE EPUB
reader. EPUB readers allow changing
the font and its size, so you can experiment
to see what makes it more readable. It
also has a search feature to find any word
or character in the entire ebook.
Because of the smaller size of the window on
a mobile device window a single page of the
original PDF may be divided into several
EPUB pages. I have noticed that the
general formatting doesn't look nearly as
good as in the original PDF's, so it may
still be hard to read. But now the
text font is scalable, i.e. changeable.
CONCLUSIONS
This
program may help in converting PDF's to make
them readable on your mobile devices, either
by just using the K2PDFOPT PDF formed from
the original or by taking the next step and
converting that to EPUB format.
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