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Re: Djvulibre testing
- From: "Bill C. Riemers" <cygwin at docbill dot net>
- To: Jukka Ylönen <mail at ylonen dot info>,<cygwin at cygwin dot com>
- Date: Tue, 6 May 2003 14:38:24 -0400
- Subject: Re: Djvulibre testing
- References: <email@example.com>
I would like to say I have an organized test plan, but I don't. There is
none. The most important things to test are "c44", "cjb2", "cpaldjvu",
c44 is for creating "DjVu" photos. They are best compared to JPEG. Usually
I compare with files produced by the "cjpeg" program. Typically a DjVu
of half the size appears about the same quality as the JPEG, but it does
on the type of the photo. The easiest option to use to control the size of
output is -size. i.e.
c44 -size 2048,4096,8192 foo.pnm foo.djvu
This would convert "foo.pnm" into a file of about 8k, divided in three
chunks so the file could begin displaying after the first 2k, update after
and finalize with the last 8k.
cjb2 is for creating bitonal images. They are best compared with single
page tiff G4 files. Typically, again you are looking at about 50% of the
size for the same quality. i.e.
cjb2 foo.pbm foo.djvu
cpaldjvu is for creating paletted images. Best compared with GIF or PNG
images. Size really varies. Sometimes images are only 10% the size of the
PNG image, sometimes they are even larger than the original pnm image.
cpaldjvu -colors 255 foo.pnm foo.djvu
ddjvu is for creating decoding the images back to pnm. i.e.
ddjvu foo.djvu foo.pnm
The rest of the commands are described in the "djvu" man page. i.e.
You might find "djvm" and "djvmcvt" interesting for creating multipage
documents. And of course "djview" is useful for viewing your DjVu document.
You can also use 'djview' to save out pnm files for use with the command
If you are curious about the xml programs, try "man djvuxml". It looks like
the command summary I had added to the "djvu" manual page for the xml
commands got clobbered in another update. So, there is no existing overall
listing of what each of those commands do.
BTW. About the speed problems. Can you let me know your operating systems
particulars. i.e. What version of Windows, CPU speed, RAM, ... So, I can
check first off if I expect faster performance. Perhaps I should try a
using "winthreads" instead of "pthreads" to see if that speeds things up.
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