InformationWeek

Managing A Digital Image System

Choose the ideal system to archive and access your valuable images

By Trudy Levy
Issue date: Nov. 25, 1996

Digital imaging, information management, and electronic publishing are hot, but not only in the traditional publishing industries. These technologies, aided by the opportunities opened by the Web, can help any company create, store, manage, and produce images. A digital image library lets a company better use and protect its valuable inventory of images or documents, while making it more accessible. The data (images) may be associated w ith other information (and thus sorted and retrieved), viewed simultaneously by several people in different locations, combined with other data (text and sound), modified without harming the original, and copied without the degradation typically associated with duplicating film images. Although the term digital imaging can describe many things, we will primarily focus on converting film libraries (slides and transparencies) to digital libraries. But much of this information can also be applied to documents, multimedia, and graphic elements.

The technology you choose depends on your intended use (prepress, printing on demand, or publishing on the Web), the means of access to images, and associated information for each image. These criteria establish how the image should be scanned, how large an image file will be, what image sizes will be available for access, and how images will be found.

These basic processes--creation, storage, and management--are interlocking pieces that use different equip ment and software, but whose configurations affect the technology requirements of the others. For example, images for prepress work should be created in high resolution, but low-resolution images are required for the Web.

Image Archive
Creating an image archive is a two-step process. First, digitize or scan the image; then, correct it to fit your needs. Choose a process that scans an image at a slightly higher degree of accuracy than you need, since you can always discard unnecessary information.

Several digitizing techniques are available: flatbed, film, and drum scanners. Most scanners come bundled with software for tweaking images, but you'll need to do even further correcting. For example, you may need to adjust color for different output devices--the CMYK (cyan, magenta, yellow, black) color system of the print world is different from the RGB (red, green, blue) system of your computer monitor. Also, some printers just print colors differently than others. You may also want to crop or rotate the image or reduce the number of colors for notebook presentation or for greater dpi (dots per inch).

Scanner accuracy is measured in two ways: resolution and color information. Resolution is defined as dpi or ppi (pixels per inch), or by size in pixels, which determines the maximum size of image output, depending on the output device's dpi. For example, a 2,048-pixel by 3,072-pixel image, divided by 300 (300 dpi), creates an image 6-5/8 inches by 10-1/4 inches.

In scanner specifications, resolution is usually given as optical or true resolution and maximum resolution, which is interpolated (pixel color is calculated according to adjacent colors). Interpolation can smooth out jagged edges, but it also softens the image.

Color information is defined by the number of bits of information per color. Most scanners produce images with 24 bits per pixel (8 bits each of red, green, and blue), or 1.6 million colors. Scanners that advertise 30 bits per pixel (10 bits per color) disregard 2 bits of d ata, leaving the 8 best bits per color.

Color's dynamic range describes how well the scanner perceives color in highlights and shadows, but it is often not specified. The more pixels and bits of information per color, the larger the image file will be, and the more accurate the representation will be.

Desktop flatbed scanners can be equipped with transparency attachments. As a rule, their range of color is narrower than drum scanners, so you may lose subtlety in the dark shadows or bright highlight areas.Furthermore, most flatbed scanners are not capable of the resolution required to scan slides for high-quality reproduction. Some scanning software includes additional image-correction capabilities, such as Linotype-Hell Co.'s Saphir flatbed for Macintosh, which includes color management based on Apple Computer's ColorSync 2.0 and prepress profiles for scanning an image at the resolution of your output device.

If you scan slides or other film, specialized film scanners are a better choice. They sca n at a high resolution (1,000 dpi) but are restricted to scanning film (transparencies up to 4 inches by 5 inches).

Drum scanners and some high-end flatbed scanners are sold for the desktop market. They can scan at 3,000 dpi with 12-bit color, have a greater dynamic range of color, and are priced starting at $20,000. If you are looking at that level of scanner, you might also want to look at outsourcing.

An alternative to a drum scanner at a prepress color house is the PhotoCD CD-ROM, a proprietary process by Eastman Kodak that is really a storage device. The PhotoCD Image Pac compression system enables a master PhotoCD to hold 100 images without losing image quality. Each Image Pac has five resolutions, the largest of which is 2,048 pixels by 3,072 pixels. Kodak's color-management system maintains the images' color accuracy on both Macs and Windows. The Pro PhotoCD does a higher-quality scanning job and holds approximately 24 images, each at six resolutions, the maximum of which is 4,096 pixels by 6, 144 pixels. Images can be color-corrected during scanning. A mistake often made with a PhotoCD is opening the files in the Photo folder--which contains information to create different image resolutions--rather than the files in the PhotoCD folder--which holds the images.

Minimal requirements for any image-editing program are color correction, contrast adjustment, cropping, rotating, and resolution adjustment. The graphics industry standard is still Adobe's Photoshop, which is not a simple program to operate but is complete and capable of subtle adjustments.

Color and contrast adjustment require more subtlety than most "lite" versions of image-editing programs can handle. One Mac program, Color-it by MicroFrontier of Des Moines, is not really a lite image editor, but it is cheaper and simpler and does color and contrast adjustment fairly well. Another standard for Windows has been Corel Corp.'s Photo-Paint, which now has a similar product available for the Mac.

Two competitors to Photoshop are Live Picture Inc.'s Live Picture and Macromedia Inc.'s X-Res, but even they don't claim to replace Photoshop. Live Picture and X-Res are faster and more flexible than Photoshop, and if you are working with large digital images, you should check them out. If, however, your staff is already trained in Photoshop, and you need to edit images only for insertion into other documents or presentations, then Photoshop is the accepted standard.

The big draw in Live Picture is its IVUE technology, which stores images using mathematical algorithms instead of rasters. It thus requires less RAM and allows much faster regeneration of an image. IVUE is the basis for the new Flashpix image file format developed by a consortium of Microsoft, Kodak, Hewlett-Packard, and Live Picture, which is promoting it as the new Web image file standard.

How the library fits into your workflow system will define your storage and management requirements. For example, you may need a static library, whose images will not be modified. Or you r digital library may be part of a workflow system where images are constantly changing, with different versions stored in the archive.

The best solution is to choose a storage and backup system that is compatible with your existing information management system, with the provision that image files will usually be larger than document files. Because standard prepress file sizes range from 60 Mbytes to 100 Mbytes, many people dedicate a server to the library system. CD jukeboxes are an option for static libraries, but they aren't competitive with an online hard drive based on cost of memory and access speed.

Another option is an advanced form of sneaker net: removable storage media. Sending a removable disk by Federal Express can sometimes be faster and more reliable than using a network.

Image Management
The image-management system's role is to retrieve images in a usable format. Your needs may range from an electronic catalog, which users browse with the help of descriptive words--suc h as a stock photography service might offer--to a complete workflow system.

What information needs to be associated with each image? At a minimum, note the photographer or illustrator's name, where you've used the image, its resolution, and licensing rights. Don't forget digital rights--just because you've been using the image digitally for prepress doesn't mean you have digital publication rights.

Most important, associate information that describes the image so that you can find it. The typical way to find images is through key-word searches. Many image-management systems were developed for stock photography and are structured for key-word descriptions.

You have several options for image management: image-cataloging programs, object databases, collection management systems, standard databases, and off-site management. Packages that have been specifically developed to manage images handle them best. They automatically enter image data (file name, resolution, how they were scanned, etc.), let you quickly browse the images, and display images at different resolutions. They also arrive ready to be used. Some let you modify their report forms, but not how they work.

Object databases are not image library systems out of the box. The simpler databases can incorporate images to a degree and are good for developing a prototype. Some object databases, such as Informix's Illustra, have components that surpass the specialized programs in image searches. But it's still safer to describe an image with key words than to depend on software to recognize it as three people on the beach at sunset.

Many simple image catalog systems are available, but most are for small image libraries or ones with minimal information associated with the image. A more worrisome drawback is that many of these vendors have a short survival cycle.

The leader in the graphics industry is Canto's Cumulus, a fairly simple client-server program that can handle a much larger catalog than the simpler packages. It has the fastest brow ser, makes data entry easy, and interacts with several graphics programs. But it works only on the Macintosh, although the company is working on a cross-platform version, due out by year's end. It is primarily a key-word system that can be arranged in hierarchical order. You can associate additional information in its notes field, which you can search, and in status fields, which can be modified, for example, to monitor workflow.

Another approach is ImageAXS Pro by Digital Arts & Sciences, which is used for many university and museum slide collections. While this is a cross-platform program, it is a standalone system that can access remote files. It can store and search for information as key words or in fields and works in conjunction with DAS's collections system. Both programs can catalog audio, video, and other documents.

An alternative to the simple image database is a standard database. Claris' FileMaker Pro 3.0, which lets you link text to an image file, works very well for developing your information structure.

Key to a satisfactory management system is determining how you search for images. A simple database lets you develop this approach before finding or developing a more sophisticated system--if, indeed, you need one.

A more sophisticated system is the image collections system, which has two forms: programs for images associated with complex information such as that used by medical users, museums, and product literature, and programs for images that are part of a workflow system.

The current standard for the first type of system is DAS's EmbArk, a client-server program that stores information in multiple categories, presents the image in 24-bit color, has security, and comes with descriptive word lists.

Two examples of programs for images that are part of a workflow system are PhotoImaging Inc.'s Destiny and Direct Data's DataWeb. Both use Web-browser technology for access over the Web or your intranet. They convert images on the fly for viewing via a modem, and they can ma nage all document imaging, including desktop publishing files. DataWeb lets you edit the original and track multiple versions. Destiny lets you download the original or a low-resolution image and add notes.

A final alternative is to have an outside company manage your archive. A prepress house, such as Color Associates in St. Louis, maintains a searchable archive of its clients' images. Color Associates' secured access system, Visionpoint, will be accessible to its prepress customers via the Internet after Jan. 1. Alternatively, library systems vendors such as PhotoImaging will maintain your off-site archive as if it were in your office.

How do you survive in this rapidly evolving environment?

Buy only what you are able to use now;
Be prepared to export data;
Build on existing strengths, but be open to changing approaches;
Stay goal-oriented, not hardware-bound.

Down the line, you may have to tweak your plan, but if you stay focused, you will be succes sful.

Trudy Levy is a partner at Image Integration, a consulting company in design of digital image systems in San Francisco. She can be reached at iminteg@aol.com .

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