-------- Original Message -------- Subject: FW: scanning encapsulated maps Date: Thu, 29 Apr 2004 16:15:26 -0400 From: Erich Kesse <[log in to unmask]> ------------------ Your message was forwarded to the University of Florida's Digital Library Center by the UF Map Librarian. I advise scanning in advance of encapsulation, the primary strategy of the University of Florida, or -- barring that -- encapsulating with extra margin for future removal and re-encapsulation. Scanning through polyester is certainly possible but raises a number of issues including: ** Moire ... and similar visual effects Polyester films will impart these visual effects. These will be more apparent with modern maps printed with half-tone technologies (... or painted by Roy Lichtenstein). ** Gamma ... and other tonal/color curve variation If faithful color reproduction is a goal, you will find that some types of polyester films introduce a grey quality -- almost all shift color-curves :: but this is probably the least of your worries re: color fidelity. Color-curves may be corrected with minor difficulty by skilled individual with access to an unencapsulated copy (or with an analyzed sample-scan of the polyester used for encapsulation -- not all polyester films are the same). ** Glare Lights can be positioned to mitigate glare effects. But, if the encapsulated map-of-size has been used, it will likely have dents and dings that make glare mitigation difficult to impossible. UF, generally, removes maps encapsulated under previous policy (pre-digital) from polyester. IF you must encapsulate in advance of digitization, consider adding vacant margin on two sides ... making the encapsulation bigger than needed for future opening and re-encapsulation. ** Plate block distortion Again, if faithful reproduction requires ability to "read" plate block impressions, imaging through polyester will distort the visual impression of the plate block. ** Flatness ... or the lack thereof during imaging Large map encapsulation processes are notoriously bad at vacating air from the encapsulation. Large maps should be imaged on a vacuum table to ensure flat image capture, without distortion. Effective use of vacuum table will require removal from polyester. Polyester will also introduce distortions should you decide to use a plotter/digitizer. [Heaven forbid it -- use of a plotter/digitizer is like scratching of finger nails on a chalkboard, with or without polyester!] If you intend to geo-rectify these map images for use in GIS, even minor distortion and glare may have a significant impact on the process. Best of luck. Erich Kesse Digital Library Center, University of Florida The PALMM World Map Collections: http://palmm.fcla.edu/map/ -----Original Message----- From: Johnnie D. Sutherland [mailto:[log in to unmask]] Sent: Wednesday, April 28, 2004 11:58 AM To: [log in to unmask] Subject: scanning encapsulated maps] -------- Original Message -------- Subject: scanning encapsulated maps Date: Wed, 28 Apr 2004 09:49:22 -0500 (EST) From: Travis Dolence <[log in to unmask]> ------------------ I am starting a major campaign of map encapsulation. However, at some point I would like to scan a number of these maps. Is it possible to scan encapsulated maps, will it hurt the scan quality? Any help that people can provide would be appreciated. Travis ---------------------------------------- Travis Dolence Assistant Professor, Map/GIS Librarian 15 Hoskins Library 1401 Cumberland Ave. University of Tennessee Knoxville, TN 37996 Phone: 865-974-3878 Fax: 865-974-3925 Email: [log in to unmask]