The workstation which was assembled to perform the investigations detailed in this report is described briefly here.
The computer is an Intel 486 operating at 66 MHz. It has 16 Megabytes of RAM and an ISA / EISA bus. A large IDE hard disk provides temporary storage. A super VGA card supporting 1280 by 1024 by 256 colors is used to support grayscale image viewing.
Most peripherals are attached via a SCSI 1 bus. These include a flatbed or sheetfed 400 dpi optical resolution scanner, a 3.5-inch magneto-optical (MO) 128 Megabyte rewritable optical disk drive and an 8-Gigabyte 8mm helical scan tape drive.
Most scanning experiments used a low-speed (1-2 MHz pixel rate) line scan 4096 element CCD camera which has a voting mirror scanning arrangement and a enlarging-type zoom lens. The camera connects to an interface in the computer using the IEEE-488 bus. The camera is used to produce 4096 by 4096 pixel images which each consume 16 MB of storage.
This camera head is mounted on a conventional copystand which provides vertical translation of the head to achieve different scanning resolutions. A software utility permits accurate focusing of the lens by dynamically measuring gradients (edge sharpness) when a bitonal item is in the field of view. A set of tungsten-halogen lights is affixed to arms on the copystand. A light-table arrangement permits scanning of transparent materials.
Printing of the outputs placed in the accompanying binders was accomplished off-site. An optical disk was loaded with the images. These were then printed on a 600 dpi laser printer at the Berkeley location after manipulation on a PC or Sun workstation there. Copies of the image data sets were transferred to recordable CD-ROM disks there as well.
Slide outputs for use in presentations were produced on a rented digital film recorder which output directly to 35mm Ektachrome film using a special internal flat-field CRT. Film provides a much superior presentation of subtle grayscale differences to a large audience.
Table of Contents - Executive Summary - Introduction - Aspects of Collection Analysis - Guidelines - Scanning & Compression - Appendixes