EP: Fenton on Prepress: A Closer Look At Digital Systems

A Closer Look at Digital Systems:

By Howie Fenton

FROM CAMERAS TO PRINT PHOTO CD

Digital photography is not a panacea. It's a tool to be used when it makes sense for flexibility and speed and with a clear understanding of how the image will look in print.

The choice of formats has been a consideration since the days when imaging meant film only. Format choice has always been dictated by the application. Sports or action meant 35 mm or 2 1/4 and food, fashion and architectural subjects meant 4 x 5- or 8 x 10-inch sheet sizes.

The same is true today for those thinking of digital capture. You must know what your final product is before using a digital camera. There is some education needed, because often a client may specify the use of a digital camera without knowing what effect it may have on the final job. What they may really be asking for is digital flexibility.

Digital's Strengths

Wayne Wyngaard, Systems Manager for Image Studios in Appleton, Wisc., a studio photography and prepress service company, makes recommendations to clients about when to use digital images.

Projects that take advantage of the technologies strengths, says Wyngaard, include:

Deadline projects. The advantages of digital photography is illustrated most dramatically when working on a tight deadline schedule. A client can walk out of a digital shoot an hour or two later with files on a Syquest cartridge and a scan is unnecessary.
Budget-sensitive projects. With digital photography, you eliminate the cost of a prepress scan. On a tight budget, that can mean the difference between printing one color image or four on a small sales sheet, or printing the piece in color rather than black and white.
Photos that will be re-used repeatedly. Digital images can be maintained on Writable CD disc, optical disk, Syquest cartridges or a large hard disk drive. They can be indexed, retrieved in seconds for preview in "thumbnail" size or dropped into layouts repeatedly, each time with all the quality of an original.

Digital or Film?

What factors determine the choice of digital or traditional photography?

The final application is the major consideration. Are color fidelity and large final image size paramount? If so, film capture is the logical choice. Digital capture is key when speed to the printed page most important.

What is the existing infrastructure at the client, photographer and prepress house? Do they all have the needed equipment and education for the digital work? The actual shooting conditions may dictate the capture method. If the subject moves or the image needs perspective control, conventional cameras are the choice. "What you don't get with digital capture is the built-in calibration afforded by a film original," says Kodak's Michael Gurley, segment manager for commercial photography in Kodak's Professional, Printing and Publishing Imaging group. He deals with photographers, art directors, prepress houses and print shops.

Film is eye-readable, Gurley notes. You see it and touch it. When it matches what the client is looking for, there is a direct comparison to calibrate to. With digital, you look at a monitor, or a dye sublimation or ink jet proof and have to make a judgment call on whether the image matches the scene.

Digital systems must be calibrated, and the whole system is only as strong as its weakest link. The calibration has to be started at one end or the other. Either at the press, working back though the chain, or at the scene working forward to the press, he explains.

You must have a proof at the scene which matches the subject and hold that calibration all the way to the press. Or, start from the press saying this is what we know we can reproduce, then take it back in steps to the front end.

Calibration tools help hold the quality through the chain, Gurley says. The Kodak Color Management System, the Q-60 target, gray scales among others are used. All the variables need to be controlled including lighting at the camera, the monitor image and the output system used.

Barriers to Digital Capture

The biggest barrier to digital photography is the existing equipment and working philosophy at clients, photographers and in prepress. If you want to use digital images, it's almost better to start from scratch and build a system around digital images, rather than trying to force fit the technology into a system built for film. Clients used to approving the image on transparencies now have to have confidence in a monitor or dye sublimation print.

Digital capture should be used when the speed and flexibility warrant, Gurley says. Catalog photography is going to be profoundly affected by digital photography, if the existing infrastructure can handle the approvals, the movement and the massive storage of data.

The technology does not however, save money if a shop is not already set up for digital. "If you buy a DCS 200 digital camera for $10,000, you need to invest another $10,000 in the CPU plus another $10,000 in a proofing device such as an XLS 8300 printer and you have to train the staff, " according to Gurley, "the money saved on film, processing and scanning is moved around."

The current generation digital camera backs are limited in file size. File size directly relates to the printed image size. Kodak's professional DCS 200 digital camera, widely used today, delivers a 2- x 3- inch 120-line screen image on the page. "Larger sensors are coming," Gurley notes, "and a larger sensor will give you a larger final image depending upon screens used, but you will need much more powerful computers to manage and store the larger image files. If your infrastructure does not have the ability to handle large files, your whole process will be slowed down."

Mixing Technologies

Taking a publication as an example, Gurley described a mix of technologies being used today. "The cover may come from a large size original film transparency going through a high end Photo Multiplier Tube (PMT) scanner, color corrected on a color electronic prepress system (CEPS) and output to separation films. Inside they may have a number of images shot on various sizes of film and converted using a desktop scanner or written to a Photo CD disc then sent to a computer for position. Late breaking news may bring a digital image into the mix that is color corrected on the fly at the desktop." The news value of the digital image is more important than its printed quality.

Applications Determine the Capture Method

A 35 mm Kodachrome slide holds about 25-28 megabytes of information. The question to ask is "does the final application require all of that information?"

"Not too long ago an advertiser specified film capture for some outdoor action illustrations because the images were destined for print ads, point-of-purchase posters and outdoor billboards. And, they wanted to hold the quality level at all those sizes," Gurley said. "In that case the final application dictated film as the capture medium.

" 'What is the final application?' is a new question people have to ask to determine the capture medium. If the client wants digital flexibility for large illustrations, it's probably best to start with film and then scan to Photo CD or Print Photo CD disc or use a desktop scanner to input the image," he says.

"I can hold up a Syquest cartridge and guess what's in there or hold up a transparency and know what it contains. If I was a photographer today with a request for a digital image, I would shoot the subject on film and then transfer it to a digital file using a scanner, Photo CD or Print Photo CD disc. Then everyone has a record of the actual scene," Gurley concludes.

Storage for Pennies per Megabyte

Things are not standing still in the digital image storage arena. Kodak worked closely with CEPS manufacturers Dainippon Screen, Crosfield, Linotype-Hell and Scitex to produce new Print Photo CD technology. The system captures and stores the image detail and dynamic range necessary for high-end image and color reproduction on a disc that holds 650 megabytes of information and the media cost is only about $20.

Kodak's David Byrd was involved with the new Print Photo CD disc technology from the beginning. According to Byrd, the new format combines the best of two worlds: high-end color electronic prepress systems (CEPS) and Photo CD technology. The new disc format enables storage of image data from licensed scanners and CEPS in both YCC and CMYK formats.

What distinguishes this new format according to Byrd? The file structure of a Print Photo CD disc is different from a conventional Photo CD disc. The format is portable across CEPS platforms and it contains ten CMYK TIFF/IT tags that are used to store and recall files used in prepress. It's also readable on standard desktop computers using a CD-ROM drive. So, the same disc can be shared beyond the CEPS system.

"For the prepress house it's like having a highly portable electronic job file," he says. "Print Photo CD discs can store both first generation and edited images on the same media along with text, line art and job tracking data." According to Byrd, prepress houses can build digital libraries of customer jobs and images, offer color-corrected digital images to the desktop market, provide media for the digital distribution of advertising for publications (DDAP) and provide source images, including those previously used in print applications for Kodak Portfolio Photo CD discs or other multimedia presentation formats.

Image sources include transparencies, 35 mm negatives and slides, dupes of color-corrected images, computer-generated art, digital photography, scanned reflective art and even video clips.

"Kodak's 1993 Annual Report was produced from scans to Print Photo CD discs. This allowed the information to be easily shared among a diverse group of interested parties. These included Kodak's Imaging Center where files are stored, Corporate Media Relations for communication to both internal and external audiences, Shareowner Relations for financial information, Adam Communications, the creative agency for design and layout, and Case-Hoyt Printers, the house that produced color separations and did the actual press work. One format serves a variety of needs, " he notes.

Byrd explains that the system initially will create Photo CD images of up to 16 Base resolution, or 2048 x 3072 pixels. Expansion to Base 64 resolution is planned. For each image on the disc, there will be at least one Photo CD image that can be used as an FPO for page creation, indexing and file access. Any related CMYK or vendor-specific files will be linked to the Photo CD images making it easy to locate and access all files for a particular job.

"Customers have told us that it's often cheaper to rescan an image than to search though files for one. Print Photo CD disc technology will solve that problem and provide a very cost-effective storage media as well, "he notes.

FENTON ON PREPRESS INDEX
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