Re: [hylafax-users] Ghostscript commands to convert PDFs

[Steve Underwood <steveu@xxxxxxxxxxx>]

On 01/16/2011 01:21 AM, Steve Underwood wrote:
> Hi,
>
> The typical recommendation for Ghostscript commands to generate a FAX 
> TIFF file from a PDF is something like:
>
> gs -q -r204x98 -dNOPAUSE -dBATCH -dSAFER -sDEVICE=tiffg3 
> -sOutputFile=output.tif -f in.pdf
>
> If the PDF is a scalable one this usually works well. If the PDF 
> contains a series of bit images of pages the resulting TIFF file has a 
> width the same as those images. The TIFF file is then unsendable. If 
> the size of the resulting images is forced with:
>
> gs -q -r204x98 -g1728x2156 -dNOPAUSE -dBATCH -dSAFER -sDEVICE=tiffg3 
> -sOutputFile=output.tif -f in.pdf
>
> The images will always (at least in every test I tried) be 1728 pixels 
> wide, and sendable. However, if the original images were only, say, 
> 850 pixels wide, the resulting FAX file contains images filling only 
> half the width of the page.
>
> Does anyone know a way to coax Ghostscript into always producing the 
> kind of result we want for FAXing? It is certainly possible to run 
> Ghostscript with the first command, check the sizes of the resulting 
> images, and then rescale when the size is wrong. However, rescaling a 
> bi-level monochrome image produces dreadful results, so its a pretty 
> desperate measure. Most PDFs containing bit images contain gray-scale 
> or true colour ones. It seems Ghostscript should be able to dither 
> them down to a bi-level image 1728 pixels wide, of reasonable quality, 
> if only I could figure out how.
>
> Steve
This command:

gs -q -r204x98 -g1728x2156 -dNOPAUSE -dBATCH -dSAFER -sDEVICE=tiffg3 
-sOutputFile=output.tif -f in.pdf

should, of course, have been this one:

gs -q -r204x98 -g1728x1078 -dNOPAUSE -dBATCH -dSAFER -sDEVICE=tiffg3 
-sOutputFile=output.tif -f in.pdf

Steve


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