RE: What image format to use

["Combs, Richard" <richard.combs@xxxxxxxxxxx>]

Sharon Burton wrote:  

> If you are also creating PDFs, you want to use a compact 
> graphics format.
> BMPs, even linked can seriously impact the PDF size.

No, no, no. There are no graphics "linked" to a PDF. There are no BMPs
in or near a PDF. The graphics in a PDF document are described in the
PDF "language," which is related to the PostScript programming language.


Many, perhaps most, of you create PDFs by first creating a PostScript
file and then "distilling" it into a PDF. That process should make what
happens to the original graphics clear: they're neither linked to nor
embedded in the PDF, they're gone.

What's in the PDF is a PostScript-like description of how to
print/render a graphic. The file size is impacted by the verbosity of
that description, which depends the amount of detail/information in the
original graphic and on the "Job Options" settings used. If the graphic
is a bitmap, then the "resolution" or number of pixels in the original
matters; a screen capture doesn't have as much information as a
high-resolution scan or digital camera image. But that's true regardless
of the file format. 

> GIFs are limited to 256 colors. If color depth matters to 
> you, PNG works well at 65 million colors. And they are 
> typically very small. And smaller graphics results in smaller PDFs.

PNGs in FM have one nuisance-level drawback: When you import a PNG into
FM (either copying or by reference), every color in the PNG is added to
the list of color definitions. Thus, you quickly end up with hundreds of
entries like "RGB 000,000,136." If you can live with that, they're
otherwise quite nice. But again, the choice of graphics file format has
nothing to do with the PDF. 

Richard 


------
Richard G. Combs
Senior Technical Writer
Voyant, a division of Polycom, Inc.
richardDOTcombs AT polycomDOTcom
richardDOTcombs AT voyanttechDOTcom
303-223-5111
------
rgcombs AT qwestDOTnet
303-777-0436
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