[pdftex] pdftex compression -- proposed addition to manual

[Ben Crowell]

George White wrote:
>Don't forget that jpeg supports variable compression levels.  You
>can't really talk about an "optimal" level without knowing more about
>the uses to which a document will be put and the characteristics of the image.

Sorry, I didn't make it very clear what I meant by "optimal."
There's a tradeoff between image quality and file size. What I meant
by "nonoptimal" was that you could improve the quality without changing
the size, or reduce the size without degrading the quality.
 From what little data I've collected, JPEGs written by the software
I use (Graphic Converter) seem to be optimal in the sense that
they can't be further optimized simply by Flate compression.

George also wrote:

>1.  pdftex does not eliminate the need for a proper image manipulation tool:
for best
      results it will be safest to convert individual images to PDF.
>2.  consider altering image color model and resolution as well as the type
of compression
      (or even converting between line art and image form -- each has
advantages in certain
      situations)
>3.  digital image storage and processing is a rapidly evolving field, so
expect new and
      better algorithms to appear and make their way into PDF in the future.

George, would you like to try merging this into the page of manual text
that's evolved so far on the list?