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Don't Trust Preview - Ever!

D

dazzer21

macrumors 6502
Original poster
Oct 18, 2005
473
4
Some might be tempted to trust Preview as a tool to proof PDFs for print.

Don't!

I have learned to my cost that it doesn't show a true representation of finished artwork, especially by way of showing overprint which can cause the artwork to look different to how it should be. One of my guys set up a job with all type as Illustrator curves laid on top of an ad in Quark XPress. Trouble was, it was all set to overprint so where there was white copy on a coloured box, nothing printed.

Preview's rendition of it showed the copy as being there. On the strength of that, the ad was approved and the printed version showed the blank box. Only use Acrobat as a reliable proofing tool. End of public service announcement...
 
Yup, Preview has trouble rendering gradients with transparencies, and probably has a few other quirks (like the one you mentioned). So, I second this advice!
 
I wouldn't trust Photoshop with a PDF either. It rasterizes them before it opens them.

Acrobat Pro has all the tools you need to proof. You can even view seps to avoid overprinting.
 
SwiftLives said:
I wouldn't trust Photoshop with a PDF either. It rasterizes them before it opens them.

Acrobat Pro has all the tools you need to proof. You can even view seps to avoid overprinting.
Click to expand...

Photography work don't require vectors and thus photoshop is the preferred app for me. For vector work of course use an appropriate app.
 
IMO the best app for previewing a PDF prior to printing is Adobe Acrobat, and more specifically, use the Output Preview option.

Found Here:

Acrobat > Advanced > Print Production > Output Preview

This will show all the seps correctly, and you can check your spot colours / CMYK colours and make sure all is as it should be.
 
I never use Preview, only Acrobat Pro. But sometimes, particularly with spot colour work and if the work doesn't involve hundreds of pages, double checking your trapping and running out separations on a laser printer straight from InDesign or QuarkXpress is the safest way to double check everything, particularly if there's a stray invisible spot color EPS point — for instance — giving you extra unwanted plates.
 
Jim Campbell said:
Just out of curiousity, what do you think a RIP is going to do to the PDF?

Cheers

Jim
Click to expand...

Yes but by opening in Photoshop and having it rasterize (most likely at 300dpi) said PDF will then have to be rasterized twice by the time it gets to the imagesetter. Also if the PDF has bitmap objects they will lose quality from the double rastering. And a vector PDF is much smaller and quicker to output then a raster one. You want to keep vector artwork vector until the RIP gets it. You always want to let the RIP do the rasterizing unless there are some sort of postscript errors/RIP issues that necessitate workarounds. Transparency and gradients can bring this about.
 
I echo other people's advice that the best proofing tool available off the shelf at reasonable cost is Adobe Acrobat Professional.

However, you can do a basic overprint check using Adobe Reader. Go Preferences>Page Display>Page Content and Information>Overprint Preview.

I lobbied for, and won this concession from Adobe when I was a member of the Pre-press Committee of the Ghent PDF Workgroup. When I asked for Overprint Preview to be included in Reader they asked why, I said, 'because you are allowing people to create PDFs that cannot be viewed correctly by their clients without buying Adobe Acrobat Professional'. They said 'Oh, we didn't realise that was a problem'.:rolleyes:

(For anyone that doesn't know, Ghent in Belgium is the 'Silicon Valley' of prepress)
 
SwiftLives said:
Maintaining vector purity for as long as possible is not a bad thing.
Click to expand...

I wasn't suggesting that you use PS to convert the vectors for use in print -- that was unclear on my part and I apologize.

I use PS to simulate the rasterization process, much as the document hitting a RIP will do. Anything that doesn't render true when PS opens it, will probably go awry when being sent to the RIP as well.

I spent over ten years trying to force uncooperative documents through RIPs, and this technique, although (I admit) lacking subtlety, is a quick 'n' dirty way of identifying possible errors in postscript/vector data before you're looking at negs and the expense of re-running them ...

Cheers

Jim
 
I hadn't thought of this or run into an issue like this yet, but good to know.

I wonder, am I a strange/wasteful person that I print more often than preview when looking for problems? I suppose half of the time I'm doing work for screen that seeing in print gives me new perspective on, so it's not really a waste, but the other half I'm doing work for print (eventually), and I suppose it lets me nip issues in the bud rather than relying on screen display and finding this out too late. Then, most of my printing jobs for myself/projects/clients/schoolwork is on my b&w laser or color laser. I've never done anything that's been sent to print for, say, a newspaper. *amateur*

But hey, even so, I appreciate posts like this.
 
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