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Old 05-16-2010, 12:47 AM   #1
syrex314
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Device: JetBook Lite
JetBook PDF antialiasing script

One thing that bugs me about the JB is that some PDFs render in an ugly, pixellated way. So for those who have Linux, I wrote a perl script that takes a PDF, and uses ImageMagick to antialias and rescale the pages for the native size of the Jetbook's screen. This is provided AS-IS, and I'm sure other software does a better job, but hey-- some of you might find it useful.

Code:
#!/usr/bin/perl
#
# pdfToPpmToPdf.pl
#
# A perl script to convert a PDF to a series of PPM files, one per
# page, then back to PDF. 
#

# file names
$inPdfFileName = "in.pdf";
$outPdfFileName = "out.pdf";
$ppmRoot = "./tmp/page";

print "converting pages to images\n";

# call pdftoppm
system( "pdftoppm", "-gray", $inPdfFileName, $ppmRoot ) == 0
# and handle an error
# this could be improved by checking the error codes listed in the
# pdftoppm manpage
    or die "pdftoppm failed: $?";

print "converting each page to pdf\n";
# convert each page to a pdf
@files = <./tmp/*.pgm>;

foreach $file (@files) {
    $file =~ /(.+)\.pgm/;    # get filename in front of prefix
    print "processing image file $file\n";

    system("mogrify","-antialias","-trim","-resize", "460", $file) == 0
	or die "mogrify failed: $?";

    print "converting $file to $1.pdf\n";

    system( "convert", $file, "$1.pdf" ) == 0
	or die "convert to pdf failed: $?";
}

print "concatenating pdf pages\n";
# concatenate pages with ImageMagic's convert function
system("convert", "./tmp/*.pdf", "out.pdf" ) == 0
	or die "concatenate pdf failed: $?";
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Old 05-16-2010, 01:59 AM   #2
jblitereader
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Um, I don't think this is a problem that only the JB has.

Me, I just stay away from pdf, period.
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Old 05-16-2010, 08:49 AM   #3
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Same here LE.
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Old 05-16-2010, 01:14 PM   #4
Ken Maltby
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Device: JetBook Lite, AuraHD, PDA, Eee Transformer
I have a number of the image type PDFs that are scanned pages from the "Backwoods
Home Magazine", they are quite readable on my JBL at 200% zoom. I have to scroll
around the page, to see the image properly through the limited window that a 5-inch
640x480 display provides. I have them on the JBL for use outdoors, as more of a
reference for implementing some of what is described in the articles. For an easier and
smoother read I have Netbooks and PCs to read them on. ( I can also read them on my
3.5" PDA display, but that is a real chore and not worth the effort.)

Image based PDFs are nice on a large display and do well for "Coffee Table" books, with
high resolution color graphics, not so great on the small black&white display. Trying to
force them to fit, results in a number of necessary compromises, and becomes a real
chore for the little CPUs in these dedicated readers.

In the case of text based PDFs with embedded graphics, (and a number of HTML based
formats, as well) it can be just a matter of preprocessing the the graphic images, so that
they match the ereaders display requirements. (I use the free GIMP2)

That said, I agree with others here that it makes more sense to just avoid PDFs, for
the small displays, whenever possible.

Luck;
Ken

Last edited by Ken Maltby; 05-16-2010 at 01:29 PM.
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Old 05-16-2010, 01:38 PM   #5
jblitereader
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Quote:
Originally Posted by Ken Maltby View Post
I have a number of the image type PDFs that are scanned pages from the "Backwoods
Home Magazine", they are quite readable on my JBL at 200% zoom. I have to scroll
around the page, to see the image properly through the limited window that a 5-inch
640x480 display provides.
When I first started reading on the JBL, I had no idea that there were other options for me out there. I only had pdf ebooks, so I thought that's what I had to stick with. I actually had to perform operation scroll right scroll left scroll down for a couple books before I told myself this was ridiculous and began collecting non-pdf ebooks.

When I first showed my brother my JBL, the first question that came out of his mouth was "does this read pdf?"

And a couple days ago, someone started a thread asking about displaying the pdf he just bought/downloaded for his girlfriend.

We as a community need to better educate people about the evils of pdf for the ebook reading community. It's the second worst format imaginable.
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Old 05-16-2010, 04:32 PM   #6
syrex314
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I suppose I'm a bit outside the target audience for most ebook readers. I'm not interested in buying ebooks-- I need a portable PDF reader. And for the most part, I'm quite happy with my JetBook for this purpose. :-D
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Old 05-16-2010, 08:55 PM   #7
Dizmatic
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Quote:
Originally Posted by syrex314 View Post
I suppose I'm a bit outside the target audience for most ebook readers. I'm not interested in buying ebooks-- I need a portable PDF reader. And for the most part, I'm quite happy with my JetBook for this purpose. :-D
I am the same type. For the most part, the JBL does a decent job.
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Old 05-18-2010, 07:23 PM   #8
kidtwisted
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Quote:
Originally Posted by syrex314 View Post
One thing that bugs me about the JB is that some PDFs render in an ugly, pixellated way. So for those who have Linux, I wrote a perl script that takes a PDF, and uses ImageMagick to antialias and rescale the pages for the native size of the Jetbook's screen. This is provided AS-IS, and I'm sure other software does a better job, but hey-- some of you might find it useful.

Code:
#!/usr/bin/perl
#
# pdfToPpmToPdf.pl
#
# A perl script to convert a PDF to a series of PPM files, one per
# page, then back to PDF. 
#

# file names
$inPdfFileName = "in.pdf";
$outPdfFileName = "out.pdf";
$ppmRoot = "./tmp/page";

print "converting pages to images\n";

# call pdftoppm
system( "pdftoppm", "-gray", $inPdfFileName, $ppmRoot ) == 0
# and handle an error
# this could be improved by checking the error codes listed in the
# pdftoppm manpage
    or die "pdftoppm failed: $?";

print "converting each page to pdf\n";
# convert each page to a pdf
@files = <./tmp/*.pgm>;

foreach $file (@files) {
    $file =~ /(.+)\.pgm/;    # get filename in front of prefix
    print "processing image file $file\n";

    system("mogrify","-antialias","-trim","-resize", "460", $file) == 0
	or die "mogrify failed: $?";

    print "converting $file to $1.pdf\n";

    system( "convert", $file, "$1.pdf" ) == 0
	or die "convert to pdf failed: $?";
}

print "concatenating pdf pages\n";
# concatenate pages with ImageMagic's convert function
system("convert", "./tmp/*.pdf", "out.pdf" ) == 0
	or die "concatenate pdf failed: $?";
WOW, thanks for sharing your script. I'm adding it to my toolbox.
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