2 SYSTEM

2.1 HARDWARE

The system used by the Decorative Arts and Sculpture Conservation Department at the J. Paul Getty Museum is an Apple Macintosh Quadra 840AV with a Radius Intellicolor Display/20 monitor, using the image manipulation software Adobe Photoshop 3.0. The minimum system requirements for using the software on an Apple system are: a Macintosh II computer with a 68020 processor (or any later model) with minimum of 6 megabytes (MB) of application random-access memory (RAM), or a Power Macintosh with a minimum of 11 MB of application RAM; Apple system software 7.0 or higher.

Expansion of the basic storage and working memory is recommended, as the image files created can be very large, ranging from 1 to 50 MB. The Decorative Arts and Sculpture Conservation Department's system has a 250 MB internal hard drive, a 1000 MB external drive, 40 MB of RAM, and a 24-bit video card.

When using Adobe Photoshop on an IBM-compatible system, the minimum requirements are a 386 processor with 8 MB of RAM, DOS 5.0, Windows 3.1 or NT, 20 MB hard disk space, and a 256-color monitor.

2.2 SOFTWARE

Adobe Photoshop is an image manipulation software that allows the editing of digital images. This program was initially developed for commercial applications in graphic design or photography. In Adobe Photoshop the images are bitmapped, or composed of a series of dots or pixels. Therefore, a straight line is made up of a series of individual pixels.

Adobe Photoshop's tools enable single or multiple images to be modified and then edited, color balanced, and manipulated. Images can be combined, enhanced with digital filters, or enlarged in areas to allow life-size documentation of deterioration or treatment. Although many different types of alterations can be made to images—ranging from perspective distortions to special effects created with filters—most conservation uses, such as documentation, can be achieved with a few straight-forward commands chosen from the pull-down menus.

The files created by Adobe Photoshop are often very large due to the complexity or resolution of the images, so an operation can take a long time to process. Speed and efficiency can be increased in several ways. One method is to work with temporary files that contain only sections of the complete larger file. At the end of a series of operations, the temporary and overall file can be merged. Another technique for the complex annotation of an image is to use a black-and-white version of a color file, since gray-scale images are about one-third the size of color (RGB) images.

2.3 INPUTTING IMAGES

There are various methods of inputting a digital image. Digital capture cameras are available and are being investigated by the Getty Museum's Photographic Services Department. Infrared images can be captured from Vidicon cameras and transferred into digital signals for storage and further manipulation. The Decorative Arts and Sculpture Conservation Department uses a color scanner system to input photographs or transparent images (either negative or positive), such as transparencies or x-radiographs. Different parameters can be set before scanning. The resolution of the scan is the most important parameter. Although scanning at a high resolution results in an accurate, detailed image, it inevitably creates a very large file, and the time for manipulation operations is greatly increased. The user needs to strike a balance between the detail of the image (determined by the resolution of the scan) and the speed of manipulation. The scanner used at the Getty is the Sharp Commercial Color Image Scanner, model JX-600. A computer service bureau can provide input by scanning photographs onto storage media for transport. Or compact discs can be made, either by supplying color transparencies or by having film directly recorded onto a CD.

2.4 OUTPUT (OR PRINTING)

Once an image is scanned into the computer, Adobe Photoshop can be used to manipulate it. On completion of the annotation, the image can be printed either to a conventional black-and-white or color laser printer or to a digital image printer. We found the Fujix Pictography 3000 Digital Image Printer best suited to our purposes. It produces high-quality color prints or transparencies by a laser-exposed, thermal development transfer method using digital image data received from the host computer. This printer provides accurate color rendering and sharpness of image. It is also possible to take files to a computer service bureau that can make high-quality prints.

2.5 STORAGE

As with all computer systems, file backup is essential. Although files can be stored on the hard drive, any system crash risks the loss of valuable content as well as time expended in its creation. Unlike the backup of word processing files, which can easily be accomplished using floppy disks (maximum storage capacity 1.44 MB), many graphics files will be too large to fit on a floppy disk. A file compression system can be used, but some information and therefore clarity is lost during the compression and the subsequent decompression. Because image files are large—from 500 bytes to 50 MB—an alternative system for storage and backup usually is required. The options include storage systems such as Magneto Optical drives, DAT drives, SyQuest systems, and CD-ROM drives. The choice of system depends on the storage size requirements; the cost of the drive and storage medium; and the stability of the storage medium. At present, only a CD-ROM system is considered to be of archival quality. As these systems are relatively new, their long-term stability must be seriously considered.

Because 30 people at the Getty Museum use Adobe Photoshop on a network, a CD-ROM system was chosen. It uses a “write once” CD system (JVC Personal Archiver), which runs on the Apple computer and allows the archiving of files onto CDs. The standard format of the CD-ROM, its large storage capacity (600 MB), and its ability to be read on inexpensive CD-ROM players make it a very reasonable solution. The comparatively recent commercial expansion of the CD-ROM market has greatly reduced the cost of both CD writers and the blank CD media, a trend that will soon reduce the cost drastically and make a CD-ROM system a cost-effective storage medium.