THOMA finally illustrated the problem of bordering, or page-edge, effects. Books and bound volumes that are placed on a photocopy machine or a scanner produce page-edge effects that are undesirable for two reasons: 1) the aesthetics of the image; after all, if the image is to be preserved, one does not necessarily want to keep all of its deficiencies; 2) compression (with the bordering problem THOMA illustrated, the compression ratio deteriorated tremendously). One way to eliminate this more serious problem is to have the operator at the point of scanning window the part of the image that is desirable and automatically turn all of the pixels out of that picture to white. ****** +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ FLEISCHHAUER * AM's experience with scanning bound materials * Dithering * +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Carl FLEISCHHAUER, coordinator, American Memory, Library of Congress, reported AM's experience with scanning bound materials, which he likened to the problems involved in using photocopying machines. Very few devices in the industry offer book-edge scanning, let alone book cradles. The problem may be unsolvable, FLEISCHHAUER said, because a large enough market does not exist for a preservation-quality scanner. AM is using a Kurzweil scanner, which is a book-edge scanner now sold by Xerox. Devoting the remainder of his brief presentation to dithering, FLEISCHHAUER related AM's experience with a contractor who was using unsophisticated equipment and software to reduce moire patterns from printed halftones. AM took the same image and used the dithering algorithm that forms part of the same Kurzweil Xerox scanner; it disguised moire patterns much more effectively. FLEISCHHAUER also observed that dithering produces a binary file which is useful for numerous purposes, for example, printing it on a laser printer without having to "re-halftone" it. But it tends to defeat efficient compression, because the very thing that dithers to reduce moire patterns also tends to work against compression schemes. AM thought the difference in image quality was worth it. ****** +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ DISCUSSION * Relative use as a criterion for POB's selection of books to be converted into digital form * +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++