Index Color in a PDF
Hi Assinippi,
When your customer saves from Adobe InDesign to PDF - and that InDesign application contains an image that can be rendered using 256 different colors - indeed, the PDF Library will convert 24 bit or 32 bit into an index color space - even if you turn of "Optimise for Web, even if you turn of all downsampling and turn of all compression, there is not methoud I have found that will prevent this conversion to Indexed color space - this is the case for both Adobe Distiller or the Adobe PDF Library (used when you 'Save As" PDF) .
I ran into this same issue when I had created a 'faked' version of the Macbeth Color Checker in Photoshop, (buy painting filled solid squars, as opposed to taking a picture of the actual item) - I then placed these images (as 1 bit, 8 bit, 24 bit RGB and 32 bit CMYK), exporting them to PDF (using PDF/X variants) and processing them using PDF color separation approaches - then i wanted to open the images up in Photoshop (using the method you descibed - that is, right clicking on the image using the Acrobat Touch up Object tool sto open the image in Photoshop) - so that I could quickly measure new CMYK densities.
- as you know, this "convert to index" fouled me up....perhaps the Adobe Photoshop team and the Acrobat team work on different floors at Adobe and don't lunch together or something.
One method that I discovered to force the images BACK into a Non indexed color space was to open the PDF file up in Acrobat, then under the File menu, select the "Reduce File size..." menu item, and when the "Reduce File Size" Dialog box is revealed, in the drop down menu to the right of "Make compatible with:" --
select "Acrobat 4 and later" - the images are no longer indexed and the image open in Adobe Photoshop CS2 (which is what I use)
This works for me when I used Adobe InDesign CS3 on Windows, saving as PDF/X-4 and "High Quality PDF" when I turned all compression off - and used Acrobat 7.
I have not tested this on any other platforms or versions - perhaps it is worth a try, perhaps not.
Maybe this helps !
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