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Oct 1, 1998 12:00 AM
Why impose electronically? With all the talk about computer-to-plate (CTP) and computer-to-press, you would think that the only thing holding up acceptance and implementation is the equipment purchase itself. However, prior to buying all that output stuff, you should probably take the first, more significant step--electronic imposition.
While there are many compelling financial and quality reasons to implement CTP and computer-to-press, the move to electronic imposition allows graphic arts firms to realize the vast majority of those benefits, usually without a significant capital expense.
Additionally, in order to take advantage of digital output devices beyond single-page production, printers will need to implement some form of electronic imposition.
Electronic page creation and assembly has almost reached complete market penetration in prepress and printing facilities. However, even with the vast majority of individual pages processed electronically, in most cases the final imposition of those pages into a press flat still is handled conventionally with masks and tape.
The degree of acceptance seems to have a direct correlation to the number of new pages handled by the facility. The more new pages, the more electronic imposition occurs. The primary limiting factors include legacy page information, either in a variety of CEPS file formats or film. In addition, there is a reluctance, usually attributed to concerns about losing the ability to do a final visual check, quickly and easily making last-minute changes, to commit to a one-piece flat.
While these concerns are real, there has been a lot of development in electronic imposition processes and systems that address most of these issues. As you would expect, they are varied in their implementation, but as with most of the electronic solutions that exist, they all work with the customary "work-arounds."
Preflight probably is the most important enabler to electronic imposition. The need to qualify all of the incoming pages to ensure process compliance prior to imposition minimizes wasted time and materials (film, plates and paper). It also allows printers to maximize the promised savings and streamline the process.
Complete, approved, electronic page files--while this may seem rather obvious, the realities of the industry reveal that, in many cases, jobs come in to a prepress production facility in pieces. It is possible to have everything but a line of type or a logo, which would hold up the imposition process.
Final press and finishing specifications also are very important. In many cases, jobs are quoted on a specific paper for a specific press. Then printers find that once the job enters the plant, it must be moved to a different press and the paper requirements have changed. While these enablers are all fairly rigid in their requirements for successful electronic imposition, many of the solutions that exist address these issues in a way that allows the "pre-design" of imposition templates. These templates also may be subsequently edited if necessary. You also may "pre-assign" your page files, before they are even in the facility, which can streamline the process further.
Full flat imposition can be accomplished in many ways, and it is important to choose the most efficient solution based on your particular needs. Some companies have found that this may includehaving various kinds of imposition software to use based on the individual job type. While this may lead to some production efficiencies, it also increases the time required for training. Plus it increases production variables, potentially leading to additional error introduction.
Most of the imposition solutions that exist today are "page-based," which means that their tool sets were developed primarily to handle page-based workflows such as books, brochures, magazines, catalogs, etc. If you are producing packaging, point-of-purchase or other specialty work, these types of packages will not offer significant benefits over a manual imposition template-based workflow.
Manual electronic imposition, much like working with film, requires that a template layout be created, usually including all the necessary process marks and indicators (i.e., color bars, register and trim marks, etc.) The imposition template usually will be created in the application that created the individual pages or objects. This allows users to more easily move or import individual pieces into position with minimal concern for cross application problems. Vector objects, or vector objects with embedded raster elements (such as those used in packaging) that were created in an application such as Illustrator or Freehand, can be imposed in a layout package such as Quark or PageMaker.
The created template can be saved and reused for similar job types. Once the template is completed, pages (or objects) are positioned onto the template, saved, checked and then printed.
While this doesn't necessarily afford the potential for process automation that electronic imposition software may, it is a very good way to allow printers to move into full flat film imposition, CTP or digital printing.
Most graphics applications provide step-and-repeat tools that can be used for some basic imposition needs. They don't, however, really address the multi-page imposition process.
Certain applications include basic imposition tools as part of their software package. An example of this is Adobe PageMaker with its "Build Booklet" plug-in. Included are a few templates for saddlestitch, perfect bound and consecutive page placements. In addition, this tool allows users to add creep and gutter dimensions. It works well for creating printer's spreads, however it falls short of other important imposition requirements--taking pages from applications other than PageMaker and adding process control marks, to mention just a few.
QuarkXPress doesn't include any imposition tools with its basic software package, although there are a number of extension developers that have tried to address the need for basic "in application" imposition for XPress. While there are a few extensions, such as Imposer 2, that have features and strengths similar to the Build Booklet plug-in, these types of imposition utilities are best suited for "light duty" work such as comps and printer's spreads.
For "heavy-duty" imposition requirements used in commercial printing, look at the standalone imposition applications. These include DK&A's INposition, Imation Presswise, ScenicSoft Preps and Ultimate Impostrip.These applications have been developed to allow more extensive control of page-based impositions.
In reviewing them, you will notice that the individual imposition requirements and features increase in direct proportion to the complexity of the software interface. It is important to note that a good understanding of imposition, printing and binding is a prerequisite for successful implementation of any of these products.
All of these products share some similarities, but each has certain unique features, too. As is the case with "in application" imposition, you need to create an imposition template. To begin, choose the type of binding (e.g., saddlestitch, perfect bound, etc.), the number of pages, trim size, bleeds, press sheet size, signature size, gripper, plate bend, etc. All of the software packages come with "pre-built" templates for more widely used impositions.
In addition, it is possible to select the type of process control marks, including color bars, either from the supplied selection or using your own specifically created ones. All of these programs handle creep, either by inserting a calculated value or the paper thickness for automated operation. After all of the necessary information is entered, templates are created. They can then be saved and reused.
For each of the applications, users need to create PostScript files of the pages that need to be imposed. The newer versions of these programs also support PDF files, which will increasingly be a better way to supply this type of imposition software. Using PDF's page-based model may preclude the need for specific origination application PostScript support in these imposition applications, which currently is an issue.
DK&A's INposition software also supports native Quark and PageMaker files, which can be a time saver if you have page corrections. There is no need to create PostScript or PDF prior to re-imposing.
ScenicSoft's Preps, as well as DK&A's INposition, support EPS and TIFF files directly into their impositions without the need for creating PostScript or PDF files first.
After creating the template, the next step is to import the prepared PostScript, PDF or other compatible files into the template. Here an imposed PostScript file is created.
While these applications operate somewhat similarly, they are also very different. The most obvious differences can be seen in the user interface. INposition has the simplest interface, and Preps the most complex, according to users familiar with all of the applications.
In addition, support, usually in the form of filters, for the PostScript generating applications varies. This support becomes necessary to address issues such as handling special (spot) colors, special overprint features, trapping instructions, OPI support, font handling, operating platforms, etc.
Since each of these applications needs to rewrite the PostScript as an imposition, and must be able to transmit any special processing instructions to the RIP, it is important to ensure that your originating application is supported in any potential imposition application. As with most competing software applications, each subsequent version upgrade increases the support for each of these outstanding issues.
Other differences include levels of additional "process" support. Presswise can interact with its TrapWise trapping application, as well as the OPEN workflow system. DK&A's software interacts with its Trapper trapping application. Ultimate's Impostrip interacts with its Trapeze trapping. In some cases, the benefits of working together with counterpart applications offer greater value than just the sum of their parts. However, it should be noted that users are not obligated to use the vendor's trapping applications in order to use the imposition software alone.
Two of these applications have different versions. Ultimate has created a "lite" version of Impostrip, which is specific to digital presses such as Xeikon-based models or Indigo. This version eliminates non-essential tools. ScenicSoft currently offers three different versions--Preps XL, Preps Plus and Preps Pro. The difference among the three is support for varying features. Therefore, you can purchase what you need for specific production requirements.
A relatively new entry into the imposition world is Dynagram Software with its DynaStrip 2.0. It can interface with other applications such as estimation software or in-house database systems. In addition, it allows for layering of press sheets, thus facilitating the placement and superimposing of objects for nesting purposes.
In an age in which shrinking margins and deadlines are the norm, companies are looking for ways to increase levels of automation in their output processes. As a result, imposition workflows in "integrated output production systems" go the next step beyond standalone applications.
By addressing the outstanding issues that prevent full automation in these output systems, many companies have developed enhancements to the process that would further support a fully automated imposition. Some of these outstanding issues addressed include: integrating legacy electronic data and digitized film, handling last-minute corrections and leveraging a single RIP process to feed the imposition to multiple output devices including imagesetters, platesetters, proofers and digital presses.
Even in these categories, the imposition solutions vary significantly. Heidelberg Prepress, for example, has integrated its popular Signastation as an option in the Delta workflow. This workstation has been enhanced over the years to give users a strong set of imposition tools, a way to integrate legacy files and a place to soft proof the imposition prior to final output.
Barco, Scitex and Screen have developed their own integrated imposition solutions also. While Barco uses an internally developed solution, Scitex uses Preps to create its imposition "scripts" and then uses its own solution to actually impose the pages on the fly to output. In each of these cases, jobs are kept as individual pages until it is time to send the imposition to an output device. This ensures quick and easy last-minute corrections.
However, it should be noted that it is possible to completely bypass or ignore these enhanced imposition solutions and use "off-the-shelf" standalone imposition solutions as discussed earlier, even though some question the wisdom of that approach.
One "standalone" imposition system that automates the process is Imposition Publisher Client Server from Farrukh Systems. The software is designed to work in a network environment using a Mac interface but doing processing functions on an NT or Unix server. It can support from five to 100 users.
Lately there have been discussions covering the issue of when the imposition should take place--before rasterizing pages or after. This issue can be debated on many levels, including data integrity, speed, editability, reuse, etc. However, all things being equal (total throughput speeds, handling corrections, addressing potential needs for reuse, ensuring data integrity), either of these scenarios could work just fine. Of course, this is dependent on your individual needs and the systems involved.
One area of confusion has been the process of "pre-interpretation." While PostScript interpretation is one of the steps necessary in the process of RIPing, in many cases it has been used to "streamline" or "optimize" the PostScript data without actually rasterizing it. Creo's Prescript product and Agfa's Apogee Pilot are two examples of this type of "pre-interpretation." On the other hand, Scitex and Rampage actually "pre-RIP" (or rasterize) their pages prior to imposition output where applicable.
So what are the real issues to be concerned with when looking at imposition workflow solutions? Remember, this can vary slightly based on your specific work.
Page independence. This is probably one of the more important issues if you are in a business that accepts partial projects over time for processing or have last-minute corrections. Try to select a solution that offers some level of preprocessed single pages, with an appropriate level of editability and integrity.
Page based vs. object based. If you are involved in packaging, POP or other specialty work, look at the way the solution handles individual objects of varying shapes. Also look at the way it handles nesting. In some cases, you may be better off doing it manually (using a layout application).
Processing time. While we all assume that the fastest is the best, in some cases it may not be the most important issue.
Correction cycles. Many solutions are tailored to handle corrections. Look at your work and analyze what level of corrections are necessary, then evaluate what tools are available. Legacy film and file support. Depending on the job, this could be a major factor. In some cases, however, it is just a transitional annoyance and can be outsourced.
Storage. Do you need to store and retrieve full flats, individual pages or nothing at all? These questions should be addressed in order to ensure your future needs. It is mandatory that you have a large enough server to handle the work-in-process. Estimate that one eight-up flat will fill at least 300 MB to 400 MB of data.
Controls. Extensive imposition control tools in the applications are critical if you are a general commercial printer with a host of varying projects and needs. However, if you produce the same, relatively simple, products over and over again, your needs may be met with a less complex solution.
Who does the imposition. In some facilities, imposition requirements are determined as early as estimating or job planning. In those cases, there is a need to ensure that the solution will support the template creation in advance of the actual page imposition itself. In addition, imposition will have to be handled at the estimator/job planner desk, not just in the prepress department.
Proofing. When working with electronic imposition, your proofing workflows may change. Ideally it will benefit you to do all of your color and content proofing in page form, either single or double.
In addition, you will need a way to ensure that your imposition is correct and that the signatures are backed up properly. There are a number of solutions to achieve that end, including both soft proofing and hard-copy proofs.
Electronic imposition has been around for some time. It has been tested and tweaked to ensure that it will be able to support the majority of jobs that exist.
The process controls necessary to implement electronic imposition are the same crucial ones needed for computer-to-plate or computer-to-press. Once implemented, the time and material savings, as well as the quality enhancements, are significant. So jump in. The water is safe. Just do it with your eyes open.