[pdftex] compression of bitmaps

Ben Crowell crowell01 at lightandmatter.com
Fri Aug 10 11:16:16 CEST 2001

Jiri Osoba wrote:

>PDFTeX uses Deflate (ZIP) compression to compress text and bitmaps 
>(TIFFs, >PNGs).

>It can use JPG images directly - they are stored in PDF with the same size.

Thanks for the information! Now I feel pretty foolish about rushing
in with my offer to code up a solution to this nonexistent problem.

Is this the appropriate place to suggest adding an explanation of this
to the pdftex documentation? I went through it pretty carefully,
and didn't find anything about this. I suppose to someone who's used
to the way pdftex works, it seems obvious. But to someone like me who
started out using Distiller, it's very surprising -- with Distiller, your
images are all normally uncompressed as late as the PS stage, and only
when you Distill does JPEG compression get performed.

Also, most people aren't familiar enough with the technical details of
the PDF format to know that JPEG and CCITT are the compression methods
used internally for compressing bitmapped images. So to them (well, to
me at least, until today!) it would be highly counterintuitive that
although pdftex accepts bitmaps in a variety of formats, you won't
get any compression (except deflate compression) unless you use JPEG or PDF.

Just my US$.02...

>You can include PDFs - compression is not changed - probably the 
>best way - >it's fast and you can tune compression (Deflate, JPG, 
>CCIT...) to save as much >space as possible.
Is there a free-software method for doing this? For line art I could do it
with epstopdf (that's what I have been doing), but is there a
jpegtopdf or something?

More information about the pdftex mailing list