November 20, 2006

ASK MORDY: Transparency, EPS, and PDF.

Today's questions from Jacob Brunny deal with the topic of transparency. If you haven't already seen my Adobe online eSeminar on the topic of transparency, you can check it out for free here.

We got a proof back from the printer today that had some objects that were vector but looked like they were rasterized. After watching your e-seminar yesterday (which was great) I looked at the transparency flattener and sure enough, we had been using EPS set at a medium resolution and those problem areas were the ones that illustrator was making rasterized complex regions. So my question is this: Once you have that EPS file set at a medium resolution, what can you do to undo that damage. I tried taking that EPS and saving it as an EPS with a high quality preset but those problem areas are still showing up. I also tried saving as native AI but it was still showing up. So can that damage be undone by saving as AI and then a PDF? Also can a printer override those settings? Can InDesign override those settings if you place a medium quality EPS into it? Also was there a place in Illustrator or InDesign where you can set the transparency level for all documents?

Jacob then followed up his original question with this:

So if you save a native AI file as a PDF/X-1a PDF does that ensure if will print correctly even on laser-jet/ink-jet printers if they don't have the overprint preview box checked in Acrobat? I am sending in an ad to a magazine but I have no clue how they will be printing it (it is a two color job using black and one spot color) I saved it as a PDF/X-1a PDF and when I viewed it, it looked off, so I referred to a post on your blog about setting the overprint preview in Acrobat and that worked but I wanted to know how that will affect the ad if the magazine doesn't have that option selected when they go to print it?

Not that I was counting or anything, but I think that was six questions Jacob :)

But they are actually great questions, and hopefully the answers will help many others looking for the same information.

Let's start from the beginning. The file was saved as EPS, and after you realized that some rasterization was occuring, you checked and found out that the file was saved using the Medium Resolution flattener setting. And the kind of rasterization that you seem to be referring to here is that of rasterized complex regions (that's when Illustrator rasterized parts of your file not because it can't preserve them as vectors, but because it wants to print the file faster). And you know from watching my eSeminar, that using the High Resolution flattener setting will disable Illustrator's ability to rasterize for performance reasons.

Well, the truth is, you can simply reopen the EPS file in Illustrator, and resave the EPS using the High Resolution flattener setting. You can do this because when Illustrator saved the EPS, it also snuck in a full native CS2 version of the file which is in an unflattened state. So you'll always be able to reopen the EPS to resave it using a different flattener preset -- well, actually, not always. Because there's one situation where saving to EPS will be irreversible. When? When you save your file as an Illustrator 8 compatible EPS. Why? Because Illustrator 8 didn't support transparency. So even though Illustrator sneaks in a native file that allows you to reopen the file, the native version is useless because it's flattened as well. So while I'm not sure what the circumstance is with your file, if it was saved as an AI8 EPS, then if it was saved using the Medium Resolution flattener setting, it stays that way... for life.

As a note, if the file was saved out of Illustrator as an EPS, then a printer can (if he knows to do this) reopen the file in Illustrator and resave it with the right flattener settings. Unless of course, you saved it as an AI8 EPS, in which case, you've shot yourself in the foot, and your printer can offer nothing to stop the bleeding (or the pain for that matter).

As for InDesign, once you place an EPS into InDesign, that EPS is already in a flattened state. Therefore, InDesign cannot change the flattener settings. As a user, you would need to reopen the EPS manually in Illustrator, and resave it with the proper settings (keeping in mind the AI8 issue mentioned above). This is why placing a native AI file (which is a PDF 1.4 file) into InDesign is key. Because then, InDesign DOES control the flattening of the file.

I don't believe there's a way to set all documents to use a specific Flattener setting automatically. Although once you do specify a setting for a document, it will stay with that setting. A solution might be to set up a template that uses the High resolution setting, and to always start new documents from that template.

With regards to your last question, when you use spot colors and transparency, the flattener often uses overprint commands to preserve the spot colors. So as you pointed out, you need to use the Simulate Overprints options when printing, or to use the Overprint Preview mode to see the results in a proof. But that is for proofing only. When the file is actually separated to plates, the file will print correctly. Simulating overprints is something that is only applicable when viewing a composite of the document. So from what you describe, you should be ok.

I hope this answers your questions Jacob, and I hope that it also answers the questions of those who were too shy (or too busy) to ask them as well.

14 comments:

Anonymous said...

Now if someone could just explain how to preview overprints to every print shop sales rep and press operator in the world my life would get a lot simpler :)

Mordy Golding said...

I'll get right on it :)

Gary Spedding, Ph.D. said...

I have had so much trouble with Adobe e-online seminars that I have given up on them period. It takes 20 minutes + to get registered (and I have high speed DHL)and then the streaming programs quit after about 2 minutes, necessitating refresh restarts. It takes over three hours this way to watch one 50-60 minute episide. So I'll continue to hope that sites like yours can provide the answers to using these Adobe programs in the absence of all the flash and hype of Adobe on-line issues.

Gary.

Mordy Golding said...

That's great feedback Gary -- I'll make sure the Adobe folks see your comments.

Anonymous said...

Would it be a solution to alter the standard CMYK illlustrator document in the Programs/Adobe Illustrator folder to 'high resolution' ? (And change the raster-effects setting to 300 dpi while yure at it?)
When creating a new doc illu will use those settings, right?

Regard,
MacMojo.nl

Mordy Golding said...

You would like to think so, but no. The high resolution setting is only something that you can apply to an EPS file when you're saving it. There's no way to apply a flattener setting just to a native Illustrator document.

Adobe looks at the flattening setting as something that you would change based on certain conditions (kind of output, etc.). Therefore, they didn't make it a setting that you could just set once and forget about it.

maeda said...

About adobe seminars, they work perfectly here, except one thing thou
The voice quality is rather poor, if they could improve that it will be nice :)

khiltd said...

You know what I think would be neat is if there were some PDF sanctioned means of defining spot varnish swatches that would both force objects which used them to overprint AND automatically preview these overprints accurately. It's obviously impossible to portray different finishes on a monitor, but even a subtle lightening/darkening of the underlying areas depending on whether it's a matte or glossy varnish would kick all kinds of fanny.

Nikosk said...

Hi there, great post. I also would like to leave question about something that has been bothering me for some time.
When you place an image with transparency in an Illustrator document and you have text showing under the transparency of the image then the text will look like it is bold when flattened.
This applies only for text within the frame of the image, the rest of it looks normal.
I've pinpointed the problem in PDF 1.4 which I gather uses a different transparency flattener than the newer versions. I also know that an AI file is both a vector file AND a flattened PDF1.4 version of the document. Is there a way to set which PDF version you save in the AI file ? Or maybe there is a way to avoid this little problem within Adobe apps?

PS.: I know I am not the only one having this problem since I've seen this in large publications (magazines, brochures)

Mordy Golding said...

nikosk, the stacking order of the objects in your file will determine whether they are rasterized. Text that falls underneath transparency effects will get rasterized. To the correct the issue, bring the text to the front.

But I can see from your question that you have some misunderstandings about PDF 1.4 and the format. I've just added a new post that should clarify things for you.

Anonymous said...

Finding your blog has been ray of hope for me today, however, I have not been able to fix my problem. I'm working with an Illustrator CS2 File that has some drop shadows on it. I'm trying to send it to a 5500 HP printer thru an Onyx 6.5 based RIP as an EPS file. When I preview the file on the RIP the area surrounding the drop shadow appears like a darker box and the only way around it is rasterizing the whole image on Photoshop. Is there any way to fixing this problem? Thanks for your help.

Anonymous said...

Great advice all around, but I'd like to add a note of caution regarding the overprints - most high-end workflows these days deal with composite input files, and thus the need to honor the overprints is very real. While you are correct in reporting that the overprints will be honored when printing as separations, a composite workflow (such as Brisque, a common one) will require that the RIP operator tell the RIP to honor all overprints. This can be set as the deafault RIP setting, but that is probably a shop-by-shop preference. In my shop, for instance, by default we do not honor overprints (been burned too many times by disappearing white objects!). However, when a job requires the it, we simply change the setting accordingly.

Dan Curry

Christian Macey said...

Hi Mordy, can you please tell me if there's anyway to access the advice offered with your now old eSeminar mentioned within this thread, especially with regard to simulating overprints and PDF 1.5 and high resolution transparency flattening.
Also, have you ever had any need to take the quick escape route and just rasterise (by what ever means) a complete vector file with transparency (maybe utilising spots too), rather than sticking with the transparency flattener preview options or PDF output flattener?

Many thanks,
Christian

Anonymous said...

Hi mordy, i've been watching ur video lesson "seeing through transparency" it is a great tutorial hats off for that learned alot. since im new to the Ai, im very confused. in some point i understood i don't flatten or rasterize the transparency(all the effects) manually it happens automatically when i save it in pdf format(which doesn't supports transparecy; I guess).later in flattner preview when rasterized the complex regions in different preset it shows different results...here is my question:- if i don't rasterize or flatten the artwork how illustrator will know that in which preset it need to rasterize a artwork. lets say i want the higest quality 100%? or how i can be sure my artwork which contains lots of transparency effects will print correctly? Please excuse me my question may be very idiotic.

Best regards
arjun giri