Googlebooks pdf compression
Lutrin
to make a very high compression (for bitonal scanned book images). I think
it use the Jbig (.*jbg) format for bitonal black/white images, but, trying
to convert some scanned book images from png (2 colors, black and white),
in jbg format, and then making a pdf, result is not compressed as
googlebooks pdf
has anyone idea how create pdf as compressed as pdf googlebooks?
--
Puppy Linux wiki: http://puppylover.netsons.org/dokupuppy
Puppy Linux Forum: http://puppylinux.ilbello.com
Windows me genuit, Ubuntu rapuere / tenet nunc Puppy Linux...
ken
> I see that Google, for books has scanned and freely downloadable, is able
> to make a very high compression (for bitonal scanned book images). I think
> it use the Jbig (.*jbg) format for bitonal black/white images, but, trying
> to convert some scanned book images from png (2 colors, black and white),
> in jbg format, and then making a pdf, result is not compressed as
> googlebooks pdf
>
> has anyone idea how create pdf as compressed as pdf googlebooks?
Off hand, no. However the JBIG2 format is quite sophisticated and has
some enhancements for compression when the type of data (text or image)
is known.
If you scan a page and then use generalised software to convert the
image into JBIG2 it will probably assume that the data is image data.
Its possible that the Google software knows that the data was originally
text, and so uses a better compression algorithm.
Lutrin
> If you scan a page and then use generalised software to convert the
> image into JBIG2 it will probably assume that the data is image data.
[...]
thanks
Do you know what software supports jbig2? I've looked at xnview and
others (like irfan view) that seems nor support this format (only jbig)
ken
> On Tue, 03 Feb 2009 16:28:40 +0000, ken ci disse:
>
> > If you scan a page and then use generalised software to convert the
> > image into JBIG2 it will probably assume that the data is image data.
> [...]
> thanks
>
> Do you know what software supports jbig2? I've looked at xnview and
> others (like irfan view) that seems nor support this format (only jbig)
JBIG2 is, if I remember correctly, covered by a number of patents.
Royalty free licences are available for *de* coding, but encoders have
to pay a fee. So I suspect the answer is that rather few applications
support JBIG2 encoding. Especially free or open source.
Pegasus (http://www.pegasusimaging.com/ixjbig2.htm) supply some products
which support JBIG2, as do Snowbound
(http://www.snowbound.com/format/jbig2.html)
By the way, if these images are in a PDF file then they must be JBIG2,
not the older JBIG (JBIG1), because PDF doesn't support JBIG1.
Ken
bugbear
I think googlebooks mainly used JPEG2000, part6, which I believe
uses JBIG as a sub-component.
BugBear
Don Lancaster
> I see that Google, for books has scanned and freely downloadable, is able
> to make a very high compression (for bitonal scanned book images). I think
> it use the Jbig (.*jbg) format for bitonal black/white images, but, trying
> to convert some scanned book images from png (2 colors, black and white),
> in jbg format, and then making a pdf, result is not compressed as
> googlebooks pdf
>
> has anyone idea how create pdf as compressed as pdf googlebooks?
My Gonzo Utilities can make extremely compact PDF files.
http://www.tinaja.com/post01.asp
--
Many thanks,
Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: d...@tinaja.com
Please visit my GURU's LAIR web site at http://www.tinaja.com
Lutrin
> My Gonzo Utilities can make extremely compact PDF files.
>
> http://www.tinaja.com/post01.asp
[...]
yes but maybe I'm very stupid since I have not any idea about running
utilities included in gonzo.ps, being in linux. I'll try to understand