Digital Proofing Workflows:
How inkjets and color management are changing the face of proofing
By Ron Ellis
Changes in technology continue to
accelerate the ongoing revolution in digital proofing. For the first time since
digital proofing systems began to appear in commercial printing companies and
prepress houses, inexpensive digital proofing systems can produce contract
quality proofs. In short, the quality is getting better and the price is
getting cheaper. As a result, digital proofing systems are becoming affordable
for many small and mid-size printers in the
The average cost of one of these proofing systems can range from $2,500 to $35,000, and can supplement or replace systems that until recently cost anywhere from $10,000 to more than $100,000.
Why is digital proofing important?
First, if you have gone computer-to-plate (CTP) or are thinking about it, then film is no longer an option and you can no longer make an analog proof. In addition, there are some real benefits that make these new digital proofing systems attractive to small and mid-size printers.
First, a reduction in the cost of a proof is dramatic. When producing an analog proof, the cost typically includes at least four pieces of film, proofing material, and the time required for the operator to register and process the materials. This cost typically is around $60-70 for a single proof. On a digital proofing system, the proof consists of paper, and ink and usually costs about $1.50. Note that the digital proof does not require the labor like the analog proof. When a file is sent, the raster image processor (RIP) will process the file and the proofer prints it without requiring manual intervention. For a small shop, this lack of manual intervention alone can justify digital proofing.
A digital proofing system is made up of three important components:
1. The proofing engine: Typically an inkjet such as an Epson 10000 or HP 5000. These proofers use six colors and can print a larger color gamut than a typical CMYK proofer can. The extra color space can be used to reproduce spot colors accurately.
2. A RIP or raster image processor, such as Best ColorProof or Harlequin ProofReady which takes the file to be proofed and converts it to the output format for the proofing engine.
3. Color management software, such as Monaco Profiler or Gretag ProfileMaker, which allows you to create color management profiles to be used by the RIP in converting the data.
What has changed to make these digital proofing systems attractive?
There have been a number of critical improvements in the past year that have made digital proofing a viable way to produce proofs. First, inkjets have become much faster. Until recently inkjets were slow, especially in cases when trying to produce accurate color. The newest inkjets can produce a 720 DPI 42x30-inch proof in approximately 10 minutes or less. The new generation of inkjets also use six colors and can show a larger colorspace than a typical CMYK proofing device, which is important for spot color proofing.
Second, the RIPs that drive these proofers do a much better job. New RIPs such as Best ColorProof make driving and calibrating these RIPs much easier and more automatic. And most of these RIPs are much better at using the International Color Consortium (ICC) color management profiles than RIPs in the past.
Third, color management software has also become much improved and can accurately produce profiles for these systems. In the past color management was like a do-it-yourself science project. Now all three of these important components work together: speed of the proofer, a good RIP that can manage color, and color profiles to describe the proof data.
Size, speed and color gamut are the most important aspects to consider when evaluating digital proofing engines.
Digital proofers range from 13x19-inch and smaller up to 42-inch wide by the length of the roll. Most proofing needs are either single-page proofing, signature proofing, or double-sided imposition proofing. For single page proofs a popular choice is the Epson 7000, although there are also a number of less expensive proofers that print 13x19-inch and can also be used for this purpose such as the Cannon BJC 8500. For either single-page or full imposition proofs the Epson 9000, 10000, and HP 5000 are popular because all are fast and inexpensive to operate.
The Teksage Spinjet is the most popular choice f or double-sided imposition proofs. The Spinjet operates with either an HP1050 or the more high-end HP 5000. (The 1050 is a four-color printer best for break and position but not as color accurate as the six- color 5000). The Spinjet can usually output both sides of a full eight-up imposition in about 10 minutes.
Although the inkjets themselves can produce pretty colors, they are useless without a RIP. The most common RIPs sold by dealers in the Northeast include Best ColorProof and Screen Proof, Imation Matchprint Color RIP, DuPont Color Station, Harlequin ProofReady, Oris ColorTuner, Serendipity Software BlackMagic and others including direct output by the platesetter/imagesetter RIP. Note that the Imation Matchprint Color RIP and DuPont Color Station are original equipment manufacturer’s (OEM) versions of the Best 4.2 Color RIP.
The most important consideration when evaluating the RIP is to make sure that the proof data is based on the same file that will be sent to the final output whether that be plate or film. This is in keeping with the RIP Once Output Many (ROOM) theory. This theory says that in order to accurately represent the final output, the proof file must be based on the same file that will be output to the imagesetter. This is commonly done by having the film or plate RIP generate an 8-bit TIFF and send it to the digital proofing RIP. For example, a PCC RIP would generate an 8-bit TIFF to send to a Best ScreenProof RIP, which would then drive the inkjet. In cases where the final RIP file cannot be sent to the inkjet RIP, using the same RIP that drives the final film or plate to also drive the inkjet may be done.
For example a
Harlequin RIP can drive a platesetter, and that same
RIP can also drive an Epson or HP inkjet with the assumption that the using the
same RIP will give similar results. (In this case, the wildcard is the
postscript file sent to the Harlequin. If it is the same postscript file,
results will be the same, but if somebody forgets to open a font when they open
it for final output, then all bests are off.). All of these RIPs
handle the file differently. Best ColorProof (and Imation Matchprint Color RIP and DuPont Color Station) can take a
8-bit TIFF, PostScript, PDF, Delta list,
In addition, many RIPs that produce final film or plates such as Artwork Systems Pageflow and Nexus, Rampage RamProof, Apogee Apogee and Sherpa, Creo Scitex Brisque and others have the ability to drive common inkjets directly. While color management hasn’t been the strong point of many of these systems, most are working to improve these capabilities. The upside of using the actual RIP that is producing plates is that it is as close to possible to using the actual file that will be making the plates or film. The downside is that it is one more task the RIP has to handle, and that some of these RIPs are not as good at color management as the third party RIPs or they may limit the type of inkjet proofers you can proof to.
While ROOM is very important, also important is the ability to process these files. Underlying the RIP are tables that control the density and amounts of ink that the RIP will lay down, and how the RIP will generate the output. In many RIPs these functions are not accessible to the average user. What this means is that with many RIPs, if you use a paper that they have not programmed this data for, the results will be bad proofs. The pre-programmed data in some RIPs is suspect and can hold you back, not letting you get the maximum color available from a printer. Some RIPs such as Best allow you to custom-build and edit these tables so you can make “paper” profiles for your non-standard papers and device, but many other RIPs don’t allow you access to these inner workings. (If you are just using standard off-the-shelf papers then this may not matter).
In addition to the paper type, most RIPs also have a linearization function. This gets the printer to a known state so that the ink data and paper data is useful. Most RIPs such as Best and some Harlequin implementations have a linearization function where you can print and automatically read strips using a spectrophotometer. Some RIPs such as Black Magic, and some Harlequin implementations require you to manually linearize. Manual linearization is time-consuming and requires a lot of trial and error.
For example linearizing with a RIP such as Best can be done in several minutes. Linearizing manually on RIPs that don’t have a built-in linearization function can take the better part of a day. If you do not have access to the ink controls you may not be able to properly linearize at all.
How the RIP implements color management
All of todays RIPs have support for ICC color management profiles. Some RIPs implement this better than others. All of today’s most common RIPs can get results by using ICC profiles, but some, such as Best, appear to work better than others, and some allow you to get there much faster than others and to have more control. Also important is how the RIP handles spot color. Some RIPs such as Best and Black Magic allow you to plug in LAB color data and accurately map spot colors. Others will use CMYK conversion data and be unable to accurately produce those colors. In addition to RIP capabilities, spot colors are also dependent on how you move the file to the RIP. For example if you input an 8-bit CMYK TIFF then you have already stripped out the spot colors via the CMYK conversion and the RIP will not be able to map certain spot colors as accurately to the proofer.
Most of the above RIPs produce a stochastic proof, one that does not contain a halftone dot. This can become problematic for some customers but has become more highly accepted as long as the color is accurate and can be matched on press.
Several of the above RIPs can produce dot proofs. Best ScreenProof can take the same 1-bit TIFFs that will be used for output and resample and output this on the inkjet proofer so that you can see halftone dots and detect issues with moiré and other screening issues. This provides an alternative to conventional proofs. BlackMagic can also read the screened data files and can output the screens, and if they don’t exist (in a format like LW and CT where the screening is done on the fly) you can program them so that they are generated as the file is processed by BlackMagic. (Remember that if you have gone CTP you do not have film at all and the only alternatives may be to spend $100,000+ on a proofer such as a Fuji FinalProof, Creo Spectrum, or a Kodak Approval).
A third RIP called Seecolor also can output TIFFs but provides less in the way of color management.
Color management is also a critical component
Many of these RIPs come with “canned” profiles to represent a Matchprint or other common proofing standard. In my experience, few customers who are trying to develop a contract proof are happy with these “canned” profiles. Most successful digital proofing installs include color management software and a spectrophotometer to read color. With these tools you can run a test chart to your current analog proofing system or press and develop an ICC profile that your RIP can then use to make an accurate representation of what you will get on press. Most commonly sold by Northeast dealers are Monaco products such as EasyColor, Proof, and Profiler as well as GretagMacbeth ProfileMaker. These products have you print a series of patches and then read them in and compare your results to the known color values. The profile developed characterizes your device and allows programs to simulate what will happen to color on the profiled device. All of these products allow you to generate and edit ICC profiles so that you can create the data your RIP needs to produce accurate proofs.
The majority of these programs require you to hook up a spectrophotometer to read the color data. The most common spectrophotometers in use are the X-rite DTP41 and the GretagMacbeth Spectroscan. There are also a bunch of newer and less expensive spectrophotometers such as Gretag’s Eye One and Avante’s Spectrocam.
To summarize, a revolution in digital proofing is occurring. It involves inexpensive inkjet printers, RIPs and color management software that is combined to create extremely powerful and automated proofing system. Some of the RIPs are easy and fast to configure, others take more time and tinkering but can help you achieve accurate color proofs. The potentials rewards are less expensive proofs, less costly consumables, less manual labor, and more accurate color. For small and medium-sized printers, this can add new capabilities, change the way you do business. And broaden your markets to a new range and type of client.
Ron Ellis is a prepress consultant specializing in workflow training and
integration. He brings a strong background to all aspects of prepress and has
been involved in numerous computer-to-plate installations throughout
If you have found this topic to be interesting and would like to know more, Printing Industries of New England offers a seminar on digital proofing that goes into greater detail and includes a hands-on demonstration of profiling, proofing and inkjet. Contact Beth White, director of association programs at PINE for more information on PINE’s seminar schedule or visit PINE’s web site at www.pine.org. You can also get more information by contacting Ron Ellis at firstname.lastname@example.org.