Conversion Benchmarking beyond Text
Although we've conducted most of our experiments on printed text, we are beginning to benchmark resolution requirements for nontextual documents as well. For non-text-based material, we have begun to develop a benchmarking formula that would be based on the width of the smallest stroke or mark on the page rather
than a complete detail. This approach was used by the Nordic Digital Research Institute to determine resolution requirements for the conversion of historic Icelandic maps and is being followed in the current New York State Kodak Photo CD project being conducted at Cornell on behalf of the Eleven Comprehensive Research Libraries of New York State. The measurement of such fine detail will require the use of a 25 to 50 ³ loupe with a metric hairline that differentiates below 0.1 mm.
Benchmarking for conversion can be extended beyond resolution to tonal reproduction (both grayscale and color); to the capture of depth, overlay, and translucency; to assessing the effects of compression techniques and levels of compression used on image quality; to evaluating the capabilities of a particular scanning methodology, such as the Kodak Photo CD format. Benchmarking can also be used for evaluating quality requirements for a particular category of material- halftones, for example-or to examine the relationship between the size of the document and the size of its significant details, a very challenging relationship that affects both the conversion and the presentation of maps, newspapers, architectural drawings, and other oversized, highly detailed source documents.
In sum, conversion benchmarking involves both subjective and objective components. There must be the means to establish levels of quality (through technical targets or samples of acceptable materials), the means to identify and measure significant information present in the document, the means to relate one to another via a formula, and the means to judge results on-screen and in-print for a sample group of documents. Armed with this information, benchmarking enables informed decision making-which often leads to a balancing act involving tradeoffs between quality and cost, between quality and completeness, between completeness and size, or between quality and speed.