8 Apr
2002
8 Apr
'02
2:55 p.m.
"Douglas H. Quebbeman" wrote:
Well, I scanned the originals as 600dpi line art,
instead of gray scale. Lineart generates bitmap
files, just two bitplanes. I'd assume that it
compresses much more easily since adjacent pixel
runs of white are next to each other and chomp
down nicely...
However... have you checked out the DjVu imaging compression
technology? DjVu is a non-propreitary superset of the iterated
fractal system imaging compression technology I read about in
Byte magazine back in the 1980s. Now that the secret's out of
the bag, everyone can have utilize extremely high-compression
if you can suffer the slight loss of fidelity to the original
(for example, the analysis will find a single ideal letter form
for an 'A', and uses that ideal letterform image when reconstructing
the document, instead of recording every pixel at every location.
For more info on DjVu, just point Google and cut the leash...
-dq
-Douglas Hurst Quebbeman (DougQ at ixnayamspayIgLou.com) [Call me "Doug"]
Surgically excise the pig-latin from my e-mail address in order to reply
"The large print giveth, and the small print taketh away." -Tom Waits
Sheet-fed scanner for most stuff, he does use a hand-scanner
for bound stuff. Like Eric, I'm pretty sure he does most pages
as 600dpi line art. I just got doing the same for a section of
a CDC manual that's in hot demand; then used Kodak Imaging
to create a multi-page TIF from the individual TIF pages. Then
print to PDF using Adobe Acrobat 4.05's PDF Writer. Yields a
367kb PDF, whereas multipage TIF was 2.1MB.
Then your TIFFs weren't compressed with the Group 4 2D algorithm, which
is the best around, until we've all got JBIG tools. Either that, or PDF
Writer reduced the resolution during conversion.