downsampling images

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From	Michael Unger <spam.to.unger@spamgourmet.com>
Newsgroups	comp.lang.postscript
Subject	downsampling images
Date	Tue, 04 Dec 2012 19:48:31 +0100
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I want to control the downsampling parameters of (JPEG) images from
within each PostScript program individually instead of modifying the
Distiller parameters ("joboptions" file) globally. The following lines
from the "joboptions" file seem to be relevant here:

|  << /DownsampleColorImages true
|     /ColorImageDownsampleType /Bicubic
|     /ColorImageResolution 300
                            ^^^ (1)
|     /ColorImageDepth -1
|     /ColorImageDownsampleThreshold 2.00000
                                     ^^^^^^^ (2)
|     /EncodeColorImages true
|     /ColorImageFilter /DCTEncode
|     /AutoFilterColorImages true
|     /ColorImageAutoFilterStrategy /JPEG
|  >> setdistillerparams

Am I correct assuming the "Resolution" (1) is the desired final image
resolution (dpi) to be embedded into the final PDF document and
"Threshold" (2) is a multiplier indicationg a resolution ratio above
which the downsampling will take place? (The JPEG iamges are converted
to EPS using the freeware utility "jpeg2ps" [1] and included via the
"run" command into the PostScript program.)

Michael


[1] <http://www.pdflib.com/download/free-software/jpeg2ps/>

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downsampling images Michael Unger <spam.to.unger@spamgourmet.com> - 2012-12-04 19:48 +0100
  Re: downsampling images Helge Blischke <h.blischke@acm.org> - 2012-12-04 22:32 +0100

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