Image Digitization: Quality and Costs, Franziska Frey, Rochester Institute of Technology
Archival scans/digital masters should be of the highest quality that an institution can afford to create and maintain. These scans should not be processed for any specific output, should not be compressed (or if they are compressed, should be done so in a lossless format) and should be reviewed intensively for quality.
The handling of original objects during the scanning process is of major concern as improper handling is the greatest cause of damage to library and archive materials. Scanning should be conducted in large clean areas and technicians should be thoroughly trained. Objects may be damaged by excessive heat and light, so scanning areas should be adequately cooled with ambient- and scanning equipment-light reduced to a minimum.
The primary goal of scanning images is to digitally render the photographer’s intent. Careful characterization of scanning hardware and software is important to maintain consistency in scanning. For example, all monitors used in the scanning process should be set to 24 bits, with a Gamma setting of 2.2 (1.8) and color temperature of 6500° K. Similarly, printers and viewing environments need to be calibrated for the quality control process. Subjective quality control includes checks for visual sharpness, laterally reversed images, dirt, skew and image completeness.
Image quality metrics include tone reproduction, spatial resolution, color reproduction, noise and artifacts.
Conversion of images into digital form will comprise 1/3 of the initial cost of one’s project, with cataloging/description/indexing accounting for 2/3 of initial cost. Ongoing costs include infrastructure and the migration of media and file formats from one form to another. Costs may sometimes be lessened through cooperative efforts and/or outsourcing of certain scanning processes.