Image Compression

[SteveClarkNo1]

Easy one. What is the general consensus on Zip versus JPEG compression in the Adobe PDF Export Presets? I've always done ZIP, but I'm reading a lot about JPEG at maximum quality being adequate for 175lpi. The same file with the images uncompressed (test) was 381mb, with Zip it was 91mb and Jpeg was 19mb. I'd say better safe than sorry and go lossless, but the IT department wants to save every byte they can. Ha anyone seen a noticeable difference in image quality between Zip and JPEG?

[Tech]

If you are in the business of publishing, regular JPG compression should be the last thing on your list regardless what IT people want to save. I don't think I would ever trade quality vs hard drive/server space. 1TB drive can be bought for less than $100 these days. What are they thinking?

Going back to lossy vs lossless, it's a yes and no question. The difference should be noticeable enough to any image professionals. It's often "no" if you are talking about average consumers. I, for one, could always tell when looking at those crappy PDF/X1 magazine ads...printing on toilet paper just make them jump out even more to my eyes.

[Lukas Engqvist]

I have looked alot at images, and would say that for a final PDF to go with Maximum JPG is fine.
(for an add you would not be doing a final since the add is usually placed in a layout program)
If you are planning on doing any post processing like sharpening however then I would have it in lossless, since artifacts would be enhanced at sharpening.
Most of the time you see poor quaility stuff the place quality is lost is other places. There are so many ways to destroy a picture. I'd say CMYK workflows with curve adjustments after converting to CMYK are a bigger cause of bad images. Many images are just plain bad because there are more people with less knowledge as content creators.

[leonardr]

If you do NOT have a requirement of PDF/X-1a or PDF/X-3, then I would recommend going with standard PDF 1.5 or 1.6 and using JPEG2000 compression. It offers a lossless mode (for those that want no loss) that still gets GREAT compression ratios compared to the classic methods.

Leonard

[Colorblind]

I use JPEG max quality as default image compression in 99% of the PDFX1a I send to publications (and I send a lot). 2400 dpi proofing result and printed results are excellent. The only exception is with documents containing images that are CMYK but have an empty channel like nothing on the cyan channel. I will then use zip compression. I had an ad once that only had magenta, yellow and black information but nothing in the cyan channel that, once turned into PDFX1a with JPEG, showed some very light cyan zones in the cyan plate of the PDF. Changed the compression to zip and the resulting PDFX1a was just like the original image channel wise.

[SteveClarkNo1]

Leonard, I would prefer X compliance just because of our customer base. That way they can preflight their own PDFs through my Acrobat Preflight profile. Is there a preflight profile available for 1.5 or 1.6? I am starting to lean toward X-4 though.

[mattbeals]

I thought JPEG2000 isn't allowed in any of the PDF/X spec's.

[edwinb]

With jpg ther is always the risk of unexpected result due to the compression capability, with zip you don't have to think or check - you know.
Edwin

[SteveClarkNo1]

That's what I'm saying Matt. If I were the designer or were accepting only native files then 1.5 or 1.6 would be the way to go. Since I the only way I can make sure I get half way decent files is to require they are X-compliant after running the designers run them through the preflight profile I have supplied to them. I figure if I give them my .csf, .kpf, .idpp and .joboptions (Export Preset), then I have a fighting chance of getting something rippable and printable.

[Gregg]

For any book projects I've always used ZIP, for the same reasons that Tech stated.

Interesting bit about JPEG2000, though.