Re: Imported / Placed Images - MORE (You Asked for It!)

["Dov Isaacs" <isaacs@xxxxxxxxx>]

Thomas,

Good question. The workings of the image interpolation option of 
Adobe PostScript Level 2 and Adobe PostScript 4 are no secret. 
It is fully documented as an optional key (default to false)
in each image's "image dictionary" per the "PostScript Language Reference
Manual - Third Edition" (downloadable from Adobe's web site in PDF
format, of course). First reference is on page 298 in Chapter 4 with
a detailed description on page 301 in the same chapter. For better
or worse, you cannot globally enable or disable the function within
a job. I know of no drivers that currently attempt to set the image
interpolation function. Photoshop and Photoshop Elements are the only
applications to allow specification of the option as part of PostScript,
EPS, and PDF generation. Acrobat Distiller propagates the key from
a PostScript image dictionary to the equivalent PDF image dictionary.
Acrobat and Acrobat Reader use the interpolate key for display and
automatically propagates the key to the image dictionaries of 
PostScript and EPS output.

Yes, you could conceivably write a program to pattern match and
add the key to either PostScript or EPS files. Of course you would
need to appropriately adjust EPS preview pointers and be very careful
about how you detected image dictionaries. Driver and application
generated PostScript can be very obscure, to say the least.

        - Dov



At 5/24/2001 11:17 AM, Thomas Michanek wrote:
>> UNIX is not my specialty and Adobe no longer provides a version of
>> Photoshop for any flavour of UNIX. Thus, my advice for UNIX users
>> of FrameMaker are effectively to capture the raw image as TIFF,
>> process the image on Windows or Macintosh to obtain the EPS file
>> with the image interpolation option, and then move the resultant
>> EPS file back to your UNIX-based system for use with FrameMaker.
>
>Dov, regarding the image interpolation option in PhotoShop for EPS:
>Does setting this option actually change the image data, or does it
>simply add a setting or key (or whatever) to the PostScript code?
>If so, would it be possible to take advantage of this interpolation
>feature by adding the corresponding PostScript code to an existing
>ASCII EPS file (without having access to PhotoShop)?
>Perhaps it would be possible to add the appropriate PS code by
>running a script on existing EPS files? (for UNIX)
>
>
>- - - - - - - - - - - - - - - - - - - - - -
>Thomas Michanek, FrameMaker/UNIX/MIF expert
>mailto:Thomas.Michanek@telia.com   (Sweden)
>- - - - - - - - - - - - - - - - - - - - - -


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