Colors 'leaking' from one eps to another inside PDF

[andrew4print]

Hi all,

I am having a rather bizarre problem. We are using an application that dynamically assembles various EPS graphics, then outputs pages as PostScript files which are then distilled (by Ghostscript) into a multi-page PDF. While working on this, I came across a strange situation. I have created a range of different graphics using gradients in Adobe Illustrator, then saved as EPS. One one page I discovered that somehow one of the colors seemed to be 'leaking' out of one of the embedded EPS graphics into another - so I had one EPS containing a magenta gradient, one containing a blue gradient, and the latter changed to a magenta tint! I figured somehow the magenta EPS was corrupted - so I recreated it and the problem seemed to be sorted. Now, the final PDF having been sent to print, laser proofs looked fine, but the final RIP to plate had the same problem as I saw, but on a different page. Wondering if anyone has seen anything like this before? If this helps, I had created a palette of CMYK-defined spot colors in Illustrator just for my convenience. Thanks for any suggestions/thoughts at all. -Andrew

[almaink]

"We are using an application that dynamically assembles various EPS graphics, then outputs pages as PostScript files which are then distilled (by Ghostscript) into a multi-page PDF."

What program, does it have a name? What version of Illustrator, the newer versions don't always save to eps reliably now that transparency is available.

[jimking]

Sorry, I have no clue to your bleed issue, however, were those laser proofs yours or the printer supplied them. If the printer supplied them are you sure they are laser, not hi-end digital proofs? The printer should use the same file to make the proofs and plates. That way you'd have noticed the error quickly instead of it getting on press.

[andrew4print]

The application is an as-yet nameless catalogue/brochure-building application built around a custom publishing engine called Web4Print that my company is supplying to a few customers. I think I have solved the problem by changing my color definitions from spot colors to global process colors in Illustrator. I (probably naively) didn't realize that that would make any difference considering that the job is being output as process anyhow, I figured the CMYK definitions would just make it through no problem. Possibly there is a combination of dangerous things happening? For instance, we are nesting EPS images 2 levels deep.

Illustrator version is 10 - not a very new version but does have transparency.

So I believe I have solved this, but would still love to hear from anyone who has seen anything similar or has any thoughts on this. One thing I discovered in the course of working on this project was that a damaged EPS can crash the distilling process, which surprised me. This was a file that was moved from one machine to another on a flaky USB key...

I actually didn't see the proofs myself but the printer referred to them as laser proofs - he was very surprised to see such a major discrepancy between the proofs and the plates.

Thanks for your input. Almaink, just hoping I'm not the 'better idiot' in your sig.   :wink:

[jimking]

The application is an as-yet nameless catalogue/brochure-building application built around a custom publishing engine called Web4Print that my company is supplying to a few customers. I think I have solved the problem by changing my color definitions from spot colors to global process colors in Illustrator. I (probably naively) didn't realize that that would make any difference considering that the job is being output as process anyhow, I figured the CMYK definitions would just make it through no problem. Possibly there is a combination of dangerous things happening? For instance, we are nesting EPS images 2 levels deep.

Illustrator version is 10 - not a very new version but does have transparency.

So I believe I have solved this, but would still love to hear from anyone who has seen anything similar or has any thoughts on this. One thing I discovered in the course of working on this project was that a damaged EPS can crash the distilling process, which surprised me. This was a file that was moved from one machine to another on a flaky USB key...

I actually didn't see the proofs myself but the printer referred to them as laser proofs - he was very surprised to see such a major discrepancy between the proofs and the plates.

Thanks for your input. Almaink, just hoping I'm not the 'better idiot' in your sig.   :wink:

Would this new application perform the same duties as QuarkXpress and InDesign?

[beermonster]

welcome aboard

anyhoo - firstly fair play for asking mate. if you have a job that will print as process - make sure your colours are process. dont assume anything - do as much as you can to make the files right, and between you and pre-press the job should be ok.

similarly - if the job's a spot job, dont be making "special" spots like "bobs blue" - coz try as we might we cant find that damm thing in a swatch book - so learn to set jobs up in the right ways, with the correctly specified colours.

and may i suggest using indesign for layouts - or a newer version of illy. ok - you could use quack (ugggh i feel dirty for saying that) but use indesign. then there's a lot more control for the next steps - pdf's, trapping, imposition, seperations etc etc you can place multiple images in one go in indesign - place multiple pdf's - or even place indesign files right into indesign - its very versatile.

ask the guys receiving your files how THEY want to receive them - not what's "easiest for me to do" (thats not you mate - thats what i hear my customers' designers saying when i get screwed files).

some folks have been known to rasterize grads in photoshop and add a little "noise" to avoid banding too

good luck

[David]

I am having difficulty understanding the "leaking" colors.
Can you post a jpeg or screen cap so we can visualize this?
Maybe we can come up with a better answer for you.


cheers and welcome to the forums,
David

[beermonster]

me hearrrrrty david arrrgh

i read it as an overlap - and possibly an overprint where the overlap is

[jimking]

Sounds like a buggy new program that is not up to speed using spots. 

[almaink]

It's transparency I'll bet. Any program thats "new" and can't handle transparency is a waste of money IMO. Postscript is a dead format.

[beermonster]

could well be alma since a vignette is counted as a transparency event - makes sense

[andrew4print]

Thanks all - I will post an image to show what I'm talking about. It's a little more bizarre than just some sort of transparency error...

You see, our application assembles the individual graphics (all EPS) to compose a page, which is output as postscript and then ghostscripted to PDF. So the header and footer graphic are always the same, the category graphics and product images are different from page to page. The very bizarre thing is what you see in the 3rd page above - the header and footer graphic appear to be 'colorized' by the category graphic. This is why I thought maybe it had to do with a corrupted EPS, because maybe there was some unclosed definition that was somehow 'leaking' through to other gradients. But it is also extremely intermittent - I've seen it so far on two different pages with no apparent reason why those pages in particular would be affected.  It appears when I redefined all my colours as process it took care of the problem. I think I had a misconception that defining a color as 'spot' wouldn't have any functional effect as my spot colors contained CMYK definitions anyhow...
Re using InDesign for layouts, point well taken - however the purpose of this application is for our customers to be able to generate print-ready pages themselves from their product data using specified predesigned options - and this is a sort of extension to our existing custom publishing engine. I imagine this sort of thing could be done as an InDesign plugin, and I think there are such things out there, but that's not our area.
JimKing, re bugs - if there are any bugs they are in the person who designed the graphics (ahem) or in the distilling stage, but our application doesn't actually touch the EPS data, just places it and passes it through to Ghostscript.
Anyhow, thanks again for all feedback and let me know if the illustration clarifies what the problem is and if anyone has any further thoughts on this. -Andrew

[beermonster]

ahh now we see


i suspect no corruption, i suspect a software bug - i suspect spot colours are the issue, so run a test - make a normal cmyk eps (just like a customer would) and drop that into a normal page - see what happens

then make a spot colour eps and drop that into the same page and see what happens

i suspect due to the spot it will somehow change the header and footer graphics

then again - with all this suspecting going on i suspect i could be wrong

oh - and convert all colours to process next time

[almaink]

Could just be an optical illusion too.  Have you checked the actual color values in the purple?
If the color of the purple also contains the background color, then it may be a blending mode snafu.

[David]

it could also be the LUT (look up table) for the spot color renders it a different cmyk value than the cmyk build, which could come down to a bug in the software.
Similar to the difference between Quark's spot color to cmyk and Indesign's spot to cmyk conversion. They both use different LUTs.