Category: mungenet

Generating Composite, Trapped PDF from InDesign

Well created, Composite PDFs are the most commonly requested format for printers in this part of the world. So, how exactly do you generate a composite, trapped PDF?

InDesign 1.5.x, 2.0.x and CS have support for Application Built-in trapping. The trapping engine inside InDesign matches many of the features of Adobe’s InRIP trapping engine; usually found in higher end RIPs from Creo, Heidelberg, Agfa etc.

Trapping is the process of changing the shapes of certain objects in a printed output to reflect the way the ink will run when printed. Each of the inks are laid down on the paper by different cylinders of the press. As the paper (substrate) are impressed by these cylinders, there might be a misregistration – where the inks don’t quite line up. In this instance, the plates contain extra overprinted areas of dots to cover up any unsightly gaps that may be left in the final output.

Highend PDF workflows today are bedevilled by the “Who is trapping this?” question. In controlled workflows, this is easy to coordinate. Prepress know which press a job is running on, and apply some visual checks on the job and may make trapping changes to the source file prior to output. However, when there is a hand-off to an unknown press and printing environment, the creator will not know the press conditions. Today’s digital workflows largely assume that the final RIP (imagesetter/platesetter) will trap the document.

In some workflows, this trust may not be enough. We need to make composite PDFs for onscreen viewing, simplicity and size; yet trap them so there are no ugly white patches at print time.

With InDesign 1.5, 2.0 and CS, the Adobe trapping engine takes InDesign created object (text and vector objects) and traps them to placed images, text and vector shapes. InDesign does not trap placed PDF or EPS objects. These are assumed to be trapped. InRIP trapping solutions will trap the entire page stream. To use Adobe In-RIP Trapping, you must use In-RIP separations. Built-in trapping limits trap widths to 4 points, regardless of the value you enter for the trap widths. For larger trap widths, you will need to use Adobe In-RIP Trapping.

From QuarkXpress, the trapping information as setup by the Trap palette only comes into play when printing separations. With QuarkXpress 4.0 and above, overprinting and knockouts as set by the palette are retained in composite Postscript output. Saving Pages as EPS from QuarkXpress 3.32 and higher does result in overprints/knockouts being retained. (see QuarkXpress, PDF, Trapping and Overprint)

InDesign 1.5.x, 2.0 and CS preserve knockout/overprint attributes in Composite Postscript output. As you would expect, Adobe’s Applicaton Built-In trapping works when printing separations.

Back to the topic at hand: A significant workflow difference with InDesign is that it can also apply Application Built-In traps when printing InRIP separations.

What are InRIP separations? Essentially, programs like InDesign send composite Postscript to the RIP with some extra commands telling the RIP to take a completed page and produce n-plates based on the colourants on the page. For simple process jobs, this would result in a page each for C, M, Y and K.

The implementation of the Postscript showpage and copypage operators have the capability of producing pages for each colourant. If the output device doesn’t have this colourant, then the alternativeSpace colourant is used; failing this, DeviceCMYK is used. There is a Postscript engine inside the Distiller, and it yields DeviceCMYK colourant output.

Acrobat Distiller has a Postscript engine inside: what does it do with InRIP separation-marked Postscript? Distiller 4.0x and 5.0.x ignore the operators for producing pages for each colourant, and produce a composite PDF. The colours stay as CMYK (or spot colours if used) if the Distiller options are left to “Leave Colour Unchanged”

Now InDesign 1.5.x and 2.0.x allow you to apply Application Built-in trapping to the composite Postscript when printing as InRIP separations. Yes, I know its a little mind bending! If you then send the resulting Postscript to Acrobat Distiller, the Distiller discards the commands to separate, but it does retain the extra “trapping” Postscript commands. The final PDF holds these trap commands, and they can be viewed in Acrobat 5.0 by turning on Overprint Preview.

The final outcome is a Composite, Trapped PDF.

Steps

1. Ensure that your Trapping settings are correct. Please consult the InDesign CS Printing Guide, the manual and your Prepress/Printer before assuming the defaults are correct.

2. Assign a Trap Style to the page. In this instance, I am using InDesign’s [Default] Trap style as viewed above.

3. Here is the File>Print dialog box. In Output, Color is set to In-RIP Separations, and Trapping is set to Application Built-In

4. To make it easier to use the same settings on the next document, you can save a Printer Style for later use.

5. This is the source document in InDesign 2.0/CS

6. The final PDF inside of Acrobat 5.0 or 6.0, (available here: Example CompositeTrapped PDF)with Overprint Preview turned on. The darker areas around the type etc. display where overprinted strokes have been applied based on the inking requirements.

7. Using Quite Revealing from Quite Software, I can also reveal the overprinted strokes separately.

For more information about Trapping, and specifically the Adobe trapping engine:

Adobe Trapping Technology (white paper)

Adobe In-RIP Trapping Workflow

How to Trap Using Adobe Trapping Technologies

Thanks to Steve Amerige, Matt Phillips for their assistance with some of the finer details.

Tuesday, 14th June, 2005

Leaving Mexico, and the sanctuary of the resort was difficult. A quick lesson in spanish has taught us many words, but none that describe the feeling of being thrown back out into the world where email and mobile phones work.

At Punta Mita resort, the only place you can get signal is out on “the rock” or in front reception – and its an amusing sight to see people holding up their blackberrys/nokias/sonys to get a few SMSs in and out. But strangely for me, the lack of communication has been refreshing. Not hearing about Michael Jackson and learning spanish was a good call.

Hour bus ride back to PVR, into Alaska (why are we flying Alaska from Mexico to California?) airlines. All checked baggage is hand-checked by a cheeky security guy. The only surprise in ours is a magic pillow of Avril’s that expands and contracts into amazing dimensions.

We board the MD-70, and fly back in time/forward in time to LAX. Tom Bradley Intl at LAX can be daunting, and not something we were looking forward to. Well, we’re through immigration (friendly agent who quoted the Immigration Act of 1976 re: I94A forms) and customs, having collected our bags, in less than half an hour.

Look out LAX, the Hodge’s are here and we’ve only spend AU$150 in the last week!

Sunday, 12th June, 2005

It’s difficult to describe the roller coaster of the last few days.

On Friday, Avril was able to fulfil a life long wish and swim with Dolphins (Not my scene, so I left the tuna-eaters to her), and we’ve walked around the resort.

On Saturday, we took a 6 hours Unimog ride through the local country-side and Sierra Madres mountains to the Pacific ocean. Visiting a beach on the Pacific ocean side of the peninsula was great. Reminded me of 14000kms away in NZ: volcanic sand beach. Our tour guide, Manuel, introduced us (or in my case, re-introduced) to Tequila. Drinking spirits in the open back of what is essentially a truck on a main road has not been one of my dreams. But a thrill, never-the-less. One could get addicted to this cactus juice. Salute! Antonio delivered us safely (but dusty) to the resort.

Sunday has been relatively easier: capped off by a visit to PV, and specifically the “old town”. The shopping could have been better; but it was difficult on a Sunday night. Buses had numbers like the WWII German Atlantic submarine fleet: U-35. They looked equally as comfy (refer: movie “Das Boot”). We found one of two Italian restaurants and had a comparative meal (we like to test the Italian food around the world) Did some damage to the cash balance, but not so much as to solve Mexico’s trade balance.

Thursday, 09th June, 2005

Up and away on Thursday 6.50am. On schedule.

Our meagre bags weigh in at 24.3kgms. I will be comparing this to what we leave with. I suggest that Customs should just impose an import duty on the nett weight of in vs. out. On second thoughts, lets scrub that one. I don’t earn that much

You know you travel too much when the guy on the Immigration desk leaving you saw last night in Customs entry.

12.5 hour flight to LAX in the 747-400 was pleasant. 4 seats spread over 2 people is a good thing. Little sleep however.

Arrive in LAX on Thursday at 5.50am. Therefore, we’ve arrived an hour before we left home. Arriving at the new Qantas arrival at T4, its a short wait for Immigration, bags waiting, waved through Customs – and we are in the US of A. My 21st visit here. We quickly walk to T3, to jump on an Alaska flight to “PV” (alias Puerto Vallarta, Mexico). You know you are in America when:

1. you have breakfast at Starbucks and the coffee is bitter
2. The guy to your right is reading ‘the art of spiritual healing’
3. the amount of carry-on luggage the person to your left has defies logic

Carry-on baggage has grown since my last visit to the US (June 2003). Its an evolutionary survival of the fittest going on: the larger predators survive.

Crowded House’s Pineapple Head plays as we wait for 50m in the LAX heat before leaving to PV.

PV, Mexico, Hola! Its a balmy 28degC, 80% humidity. Quiet dinner, and we are asleep at 11pm local time. +36 hour day with less than 3 hours of light sleep means we sleep the sleep of the peaceful.