I have a PDF that Acrobat Pro X fails to "downgrade" to PDF 1.4, so that it is compatible with Acrobat/Reader 5.
My usual technique is to run the "Compatible with Acrobat 5" Preflight profile. But it fails with "The PDF document uses features that require at least Acrobat 6.0 (PDF 1.5)", specifically: "JPEG2000 compression used (2 matches on 2 pages)". The details for those 2 offending images are the same: Color image 648.0x864.0 pt 266.0 ppi "Black" "PANTONE 334 CV" overprint: off
I have also tried File → Save As → Optimized PDF… then selecting “Acrobat 5.0 and later” for the “Make compatible with:” pull-down. I've tried leaving all the boxes checked (the default), and unchecking all the boxes (Images, Fonts, Transparency, Discard Objects, Discard User Data, and Clean Up) since the "Online publishing (optimize for quality)" Preflight profile I'd already run should have addressed all those requirements. But the results are the same.
I usually have no problems avoiding JPEG2000 compression with the "Compatible with Acrobat 5" Preflight profile. What is it about these images that is causing the problem? How can I work around it?
Do you have a sample file you can post here? I don't see why the PDF Optimizer would have an issue converting JPEG2000 to JPG to go down to PDF 1.4 (Acrobat 5 Compatibility).
On a side note, it looks like the image may be a duo tone: Black and PANTONE 334 CV. This may be part of the issue. JPEG2000 works on color and grayscale, not sure how it would do with duotones.
I'm confused, too, since this usually works.
Unfortunately I can't post the file here because it is very large (41.9 MB, 1,280 pages) and is copyrighted IP. I'll see if I can extract the offending images...