CMYK Index images in PDF
CMYK Index images in PDF
Could you elaborate on these?
"- indexed pictures in CMYK or any of the above" Do you mean indexed mode? How do you create a CMYK indexed picture? CS3 won't do it.
Hi Gordon,
Oh, how I wish your were wrong ! Unless the CS3 you speak of is Photoshop CS3 - but hardly anyone creates the final realy to print PDF from Photoshop. Designers and publishers place images into things like Adobe InDesign CS3 and then (hopefully) export directly to PDF using the Adobe PDF Library, but even if they didn't (and print to PostScript and Distill) you still can get Indexed RGB or Indexed CMYK images in your PDF - and there is no setting you can change to stop that from happening !
If you happen to be placing any normal RGB or CMYK image that could be represented with 256 distinctly different pixel values, lets say - a picture of an orange on an orange background - when you export to PDF, they get indexed - ALWAYS.
need an example PDF ? --> Multi_bit_all_in_one_target_pdfx.pdf
ftp://Scans:[email protected]/indexed/Multi_bit_all_in_one_target_pdfx.pdf
if this link for some reason does not work for you;
FTP host: ftp.ioflex.com/
User name: Scans
Password: G4-Tiff
Directory: indexed
File: Multi_bit_all_in_one_target_pdfx.pdf
Near the center of this PDF (third row down) are two images - the Greytag/Macbeth Color Checker Color Rendition Chart (by Bruce Lindbloom). While both were absolutely 32 bit CMYK image files when imported into InDesign, when this is exported to PDF/X-1a, (or a NON - PDF/X PDF, like "High Quality" setting) - while the images are still CMYK - they are now Index Color space.
Please note that while other images may have been (and have labeled that suggest) they are 8 bit and 24 bit, when you export to PDF/X-1a, the Adobe PDF Library converts them as well - in some cases, an 8 bit greyscale becomes DeviceN - and (of course) a 24 bit RGB image is converted to 32 bit CMYK.
This test file is NOT about testing any color management workflow - I created this test as an example file of issues for people who want to test their CMYK to CMYK conversion solution - for example, if you want convert a CMYK PDF into a different GCR CMYK PDF.
Some workflows or approaches sometimes fail to address images in certain conditions - this PDF does NOT cover all of them BTW, so do not think you are totally safe if you can convert all of the images in this PDF, but this PDF does contain several common image types.
I think perhaps there should be an effort to create a standard test suite for this - anyone on the forum from GWG ?
Michael Jahn
Slightly used PDF Evangelist
Simi Valley, California
