The Cold, Hard Truth About Computer To Plate

By Howie Fenton

How is computer to plate (CTP) printing technology like a household microwave? Give up? According to one of the manufacturers the enormous changes that occurred with the microwave are predictive of those that will occur with CTP.

How, you ask? A conventional oven takes a long time to cook while the microwave takes a short time just as traditional platemaking takes a long time and CTP a shorter time. In addition, the microwave changed the frozen food business and surrounding industries just as CTP will change the plate making and the printing industry.

In contrast, another manufacturer says that there is little to no advantage when CTP is compared to outputting imposed pages from a imagesetter. Clearly CTP is a controversial subject. Considering that CTP is the hottest subject in printing today you have to wonder if the claims are accurate. In this article we will examine the claims, issues, obstacles, and the products.

The first aspect of CTP technology that makes it difficult to understand is the terminology. For many people the concept of CTP conjures up images of writing a metal plate on one of the new platesetters such as the Creo, Gerber or Krauss units. But, CTP can be any system in which a plate is exposed from digital information. This includes: paper plates in laser printers, paper and polyester plates in imagesetters, metal plates that are burned on-press (GTO-DI), and polyester or metal plates from platesetters.


Another confusing aspect of the CTP story is: why are printers paying $200 - $400,000 for the new platesetters. Depending on which trade show you go to or which manufacturer you talk to the motivating factors include: more ecologically friendly, faster turnaround, higher quality, lower costs, more efficient workflow and reduced labor costs. At first blush each of these advantages appear clear, but if you dig a little deeper you find that they are more complicated then seem.

For example, the at first glance the environmental issues appear crystal clear. In the conventional workflow both film and plates are processed and result in hazardous substances. Considering that film processing often results in more substances then plate processing, the elimination of film should reduce a large portion of toxic substances.

However some platemakers and plates generate similar silver-halide by-products as film which make the reduction in hazardous materials and the ecological advantage is less clear.


When making plates from film there is the possibility of the quality problems. Eliminating film, such as color separations, duplicate film and final film with its inherent dot gain promises enhanced image quality.

Potential problems include scratches, problems with processing variability, problems with dimensional stability, and problems with imperfect contact between film and plate during exposure. The chances of these problems occurring with CTP are reduced but not eliminated. This is best exemplified by the elimination of the contact step.

In addition, problems with the dimensional stability of film or polyester plates is eliminated. But, plates, like film, still require processing therefore scratches and problems due to processing variability can still occur.

Some claim that CTP will result in better registration on press. If true then this could lead to quicker start up and less paper wastage as the press run begins. However, several of the platesetters use the side of the plate to register or align the plate and the sides of the plates are not perfectly square, which is essential for this type or registration or alignment.


One obvious way to increase productivity is to shift from a manual imposition to a electronic imposition and workflow. Imposition is the process of arranging pages in the appropriate order for transferal to film or plate. In addition imposition must take into account the way the pages will be folded, bound and cut.

Manual imposition is one in which single pages are created and stripped together manually and individually. It is a labor intensive task. In contrast, procedures that create imposed signatures electronically are more productive.

Manual unproductive workflows are those in which single pages are created from a PostScript imagesetters or film plotters (i.e. Scitex, Linotype-Hell or Crosfield) and imposed manually. Regardless of how the individual pages are created, these single page methods have to be stripped together which is labor intensive especially when they are four color.

None of the platesetters would be useful without imposition software. Many of the devices offer their own imposition programs, and most are compatible with the imposition software currently available.

Again, using a platesetter with imposition software appears to be a clear advantage. However, this advantage becomes less clear when you compare the CTP output to film output from a large format imagesetter using imposition software.

With a large format imagesetter and imposition software 4 or more pages can be printed imposition on film. If you print out 4 or 8 pages in imposition on film then the advantage of writing imposed pages on a plate is reduced. In other words, imposition is one of the ways CTP is more productive but imposition can be performed on film as well.


The possibility of saving money is always a driving reason to consider any new equipment purchase. With CTP the savings can result from imposition software, decreased stripping, decreased film, decreased processing and less work in the stripping, proofing and platemaking departments.

Obviously, if you eliminate film the cost of production should be less. If you make 500 plates a week or 25,000 plates a year and save an average of $10 on film and processing then eliminating film will save you $250,000 year. In addition, you should realize a savings from the elimination of the masking material and the chemistry to process the film.

Again if we dig deeper we see that the advantages become less clear. If the plates are more expensive then the savings resulting from eliminating film can be lost. In fact, most of the "direct to" plates are more expensive then conventional plates by a factor or two or more. If the plates cost $10 more then the film and processing savings would be lost.

Another way to reduce costs would be to decrease labor costs, which is a nice way of saying eliminating staff. In larger plants you may be able to eliminate one stripper or platemaker per shift, in smaller operations perhaps half a person in each department. If the staff in these areas cost the company $50,000 with all benefits included then savings could amount to $50 - $100,000 per year.

#1 Hurdle - ROI

There are three hurdles interfering with the acceptance of CTP: return on investment (ROI), supplied film, and last but not least color proofing. With the platesetters ranging from $200 - $400,000 it would take you 2 and 4 years to achieve a payback or ROI (return on investment) based on a $100,000 savings in labor a year described earlier.

Return on investment is a calculation that becomes more and more important as technology becomes more and more expensive. With imagesetters costing over $200,000 and platesetters costing over $400,000 CTP is an expensive technology.

Today the average life cycle for electronic prepress products ranges from two to four years. That means that whatever prepress product you buy today, chances are you will most likely buy another to replace it in 2 - 4 years. This may sound like an exaggeration but if you ask your colleagues what their doing with the scanners, computers, proofers or imagesetters they bought three years most will tell you they bought something else to do the work.

The problem, of course, is what if you discontinue using a piece of equipment before you pay it off. The answer is that you accumulate debt. Since most electronic prepress equipment is replaced within 3 years you have to pay it off before you put in a dusty corner.

The take home story is that if you are a small to medium sized printer and you can't pay for your equipment in three years then you shouldn't buy it. Why? Because chances are you will have to replace that equipment before you achieve the ROI.

#2 Hurdle -Supplied film

Working with supplied film is a big issue for publishers, especially magazine publishers who commonly accept film from advertisers. The problem is how do you combine the supplied film with the rest of the pages which have been created by the computer in a digital format. The options includes: scanning the film, leaving holes or windows on the plate and exposing the film using conventional projection methods, or implementing a standard for digital transmission of ads.

The scanner getting the most attention is the Eskofat scanner which can scan negative film, descreen it and rescreen before going and writing it onto the plate. The question is: can color separated negatives be scanned as high-resolution line art (preserving all the dots) and then be reimaged on the plate? Or can the negatives be scanned, descreened and rescreened to the plate?

There are a few shops scanning supplied film. However, both options are fraught with potential problems, especially if high quality printing is expected.

Another solution is to image the plate with the CTP system and then use projection methods to burn the plate from the film. This option is also fraught with potential problems. First, the plates that are imaged from a laser beams may not print well from projection methods. In addition, the plates printing properties can change over time. Therefore, if a plate is imaged in a platesetter and then put off to the side until the film arrives the older images may print different then the new images.

An interesting analogy which helps to illustrate this point is one involving waxing your car. Imagine that you waxed half your car on Monday morning and the other half of Wednesday morning. When it rains on Wednesday afternoon the half waxed earlier that day will cause the water to bead up.

But for CTP to succeed this issue will be overcome. It may be a scanner solution or perhaps a digital standard for ad transmission. Although a slow process, standards such as TIFF-It are being developed and accepted which should eliminate the need for advertisers to provide film.

#3 Hurdle - Color proofing

The last and most controversial hurdle is color proofing. One of the most difficult issues for experienced printers and clients is the realization that CTP means there is no intermediate film from which to make a film based proof such as a Matchprint or Cromalin. With no film based proof, how can the client be assured that the final pages are acceptable, and how can a printer be sure that the client won't reject the job?

Several of manufacturers point out that you can feed film through their machines, and from this film you can make a traditional proof. Since you are using the identical rip and imager, they say, any PostScript errors will be caught on film. The main costs are the exposure time and the film itself, and perhaps the need for a separate film processor. The problem is that using a platesetter to output film eliminates all the advantages of going direct to plate. And it could cost more, create more harmful substances and take more time then the old way you made plates.

Two other proofing options exist: loose (random or scatter proofs) and soft proofing. Regardless of if you call them loose, random or scatter proofs, they all refer to the same thing - individual page or image proofs. The strategy is to use these individual proofs during the color correction and electronic stripping phases of work and eliminate color proofing for the balance of the job.

After the job is fully assembled, RIPed and ready for platemaking, a electronic or digital blueline equivalent can be made in order to check for proper assembly. Large format black and white proofers are made by companies such as Calcomp and Escher-Grad, while the large format color printers include the DisplayMaker by LaserMaster and the Cactus.

Soft proofing allows you to look at a monitor to see the final image. Of course, when looking at a 8 letter size pages on a 13" monitor you can't see much detail, but perhaps you can determine if the imposition is correct and images on the right pages. In addition, the problems of trying to match color from a monitor are well known.

Viability of digital proofing

There are two possible solutions to the proofing problem. One is using digital proofing, the other is using no proofs. Any proof that does not require an intermediate film can be considered a digital proof. Digital proofers can include thermal transfer printers (i.e. QMS, Tektronix), color copiers (Canon, Xerox), dye sublimation printers (Kodak, 3M Rainbow), high quality inkjet printers (Iris, Stork) and Direct Digital Color Proofing devices (Kodak, 3M).

If you've attended the GCA's Spectrum Conference in the last few years you probably attended the infamous "Dots vs. No Dots" debate. If not, suffice it to say that one of the last remaining roadblocks to full-blown CTP printing is the acceptance of digital proofs by the advertising community. A few pioneers, like Time and Family Circle, are leading the way, encouraging digital advertising, but there are still economical and logistical issues to deal with. For example, advertising agencies may need multiple proofs, as many as 1,000 in some cases.

What about the DDCPs. The two highest quality DDCP's are the Kodak Approval and 3M Digital Matchprint (recently discontinued). While high quality, fast, and accurate predictors of color they are expensive ($200-$300,000), limited in format size, and have their own RIPs, opening the possibility that rip errors and peculiarities will be different on the proofer.

The first attempt to address these issues has come from Kodak that has announced a thermal platesetters that uses the same RIP as the Approval. The thermal plate is exposed with an infrared laser diode in an Ektron imagesetter. The Ektron uses the same RIP and print engine as the approval. Therefore you would expect that proof from the Approval would be indicative of the plate from the Ektron. Kodak is very careful to position this product as a test of market acceptance and marketability.

The Case Against Proofs

At the fall Seybold show David Brown, the Director of Imaging Products at Creo Products said, "Eliminate proof wherever possible. They slow down the process and diffuse responsibility. Proof only what has to be proofed and prove it to the owner. Whoever is responsible for that process step, look for the fastest and cheapest proof that covers what you care about. And do it as early as possible in the production cycle. Publishers must take the responsibility for delivering the right data".

Is it possible to do away with proofs? A few decades ago, press proofing was the norm for process color approval, a relatively slow and expensive method of proofing, and one which, surprisingly, was often not a good predictor of high-speed web press runs.

A [laminate] proof like a Matchprint or Chromalyn proves color content, layout trapping, and much more at the same time. That's fine, but it comes late in the production cycle. It's slow and it's quite expensive. We'll get the full benefits of computer-to-plate if we can separate some of these proofing components and move them earlier in the work flow or eliminate them all together. So who proofs what?

It is hard to believe that we can skip the proof for color critical jobs and long runs. There is just too much money at stake. On the other hand a great deal of printing is routine and day after day they learn what to expect from each other.

Where cost and turnaround time are serious goals, we think that proofing will become an optional step. Where top quality and 100k+ run lengths are in the offing, the client will be willing to pay a couple of hundred dollars extra to run out the film just for proofing.

The Products

Looking at the table you can see that there are several features which differentiate the platesetters. In brief, the maximum plate size determines which presses can be. The laser beam and intensity determines which plates can be used which also impacts the cost. The plates determine the run length, quality and cost.

The RIP and resolution has an effect on the maximum line screen as well as the screening technology which can be used. The RIP and writing engine determines the productivity. The media such as aluminum or polyester plate or film, determines the flexibility of the workflows as well as the run length.


Since the fall 1994 trade shows such as IPEX, Graph Expo and Seybold the CTP technology has become one of the hottest topics in print production. This was very clear at the recent GATF Tech Alert show in Chicago when over 300 people huddled together for the first day to hear about the existing CTP products and pre-DRUPA announcements of new products.

Even though there is tremendous excitement about CTP technology the number of installed units is quite small. In addition, since many are in Beta testing or have been sold in a partnering relationship, many of the users are reluctant to speak candidly.

As a result that the advantages and disadvantages are unclear. For some companies the advantages are clear. If you go to any of the shows listen to the Beta testers they talk about increased productivity, decreased cycle time, reduced costs and fast ROI. However, many of these sites use their platesetter to create over 400 plates a week and those plates are used for black and white printing. If you don't fit that criteria then the advantages are less then clear.

If your considering CTP think about the following. How you will deal with the three hurdles? Remember that the proposed advantages are more complicated then they appear at first glance.

Finally remember that CTP is simply one workflow option and like all others it has unique advantages and disadvantages. Compared to single page workflows it has tremendous advantages, but when compared to 4 or 8 page imposition of film from imagesetters the advantages are less clear.

Considering the purchase of CTP products and wondering where to start? Whenever asked to perform a workflow analysis and determine the feasibility of any new purchase I work backwards. First what is the goal. Second map out the different options to achieve that goal and calculate the costs, anticipated productivity, bottlenecks and future growth. Lastly consider the cost/performance ratio and ROI of each option. At this point you will have enough information to make a good decision.

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