Re: reduce PDF file size...and PDF images displaying as grey boxes?

["Thomas Michanek" <thomas.michanek@xxxxxxxxx>]

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From: "Ryan Gibson" <rgibson@xxxxxxx>
> couple questions about Frame files with graphics imported by reference and
> how they come out in PDFs:
> 
> 1) Can imported file size/format affect final PDF file size?

If your question is whether differences in image file size and/or
format may influence the final PDF file size, the answer is yes.
Generally, the distilling process from FM files via PostScript
to PDF doesn't know or care about the initial image format, so
a GIF or a TIFF or a BMP file doesn't matter. However, different
image formats may support and use color depths differently.
For instance, GIF only supports 256 colors, so using a GIF
instead of a 24-bit TIFF may very well reduce file size, since
the color information may have been reduced. Of course, this
will influence the quality and appearance of the image.

> Our PDF file sizes seem very big to me--5+ MB for a 300pp manual with 160
> screenshots. One reason might be that we have been using TIFF format for
> screenshots. Do you think we can reduce our PDF file size by switching to
> JPG or GIF? We used to print more guides, so I think that's why the
> standard is TIF. But mostly we distributed PDFs now, so TIFF is overkill.

The resulting PDF file size depends much more on the distiller job
options than the original image format. You can reduce PDF file size
by tweaking your job options. As always, there's a price to pay, and
you have to balance file size against quality.

> 2) Why do all images in PDFs display as grey boxes?
> 
> What I did:
> 1. Ran all the TIFF screenshot images (160 in all) through a batch
> converter to convert to JPEG.
> 2. Ran a framescript on my FrameMaker book to re-point all imported
> graphic paths in book to the *.jpg version of each image.
> 3. Open all files in FM book, save them, and close them again. (The first
> time I open Frame, I get get an error about import graphic filters and
> file formats changing. But after saving each file in the book, this went
> away...I have a feeling this is causing my current problem with images
> showing as grey boxes in PDF)

Your feeling is correct. Apparently, the FrameScript you're using isn't
doing its job properly, or you use it in ways it wasn't intended for.
It's not enough to change the file name of imported graphics, the
graphic filter information must also be changed, which is tricky.
FM doesn't really care what your file names are; you could very well
have a TIFF image with a .jpg file extension. My guess is that FM
tried to open the new JPEG files with the previously used TIFF filter.

Instead of bothering with changing the image format, concentrate on
reducing the color depth of the images and tweaking your job options.
As others ave said, JPEG format is not a good choice for screen dumps.

_____________________________________________
Thomas Michanek, FrameMaker/UNIX/MIF expert
Technical Communicator, Uppsala, Sweden
mailto:Thomas.Michanek@xxxxxxxxx
http://go.to/framers/
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