Wednesday, December 8, 2010

Flatbeds VS Digital CopyStands

There has been a very interesting discussion on the Visual Resources Association (VRA) list serve comparing scanning stations that are flatbed scanners and those are copystands with a digital camera.  The digital copy stand seems to be the favorite among those with extensive workflows because of its consistency and speed.  However, when you are scanning printed material which has been printed using a dot pattern such as most books, brochures and programs, people seem to lean towards the flatbed.  The problem with dot patterns and half tones is moire patterning which is defined at "moiré pattern (pronounced /mwaˈreɪ/ in English, [mwaʁe] in French) is an interference pattern created, for example, when two grids are overlaid at an angle, or when they have slightly different mesh sizes."  Thus, you have pixels and you have dots of ink, which results in moire or ripples across your scan.
Many find a flatbed scanner, which was described by a digital copyststand advocate as a digital camera with a very shallow depth of field, the preferred method with this type of material, because most scanning software have a  descreening function. For those curious, at this time the Epson 10000XL appears to be the flatbed of choice.
However, if you are using the copystand with digital camera set up, some "tricks" of the trade were shared.  The basic one appears to be to rotate the original material, shoot it and then straighten it in Photoshop. The rotation is minimum, about 8 degrees and should be done by trial and error as different printers have different dot patterns.
Another trick offered by the generous VRA listees was to correct  bleed-through from the backing page, by using a sheet of matte black paper can help prevent this, and sometimes help minimize background “checkerboard.”

My thanks to the VRA List, in particular: Rebecca A. Moss, Howard Brainen, Eileen Fry, Mark Olson, Chris Strasbaugh and Ross Wolcott.
For those looking for more information about scanning stations, you can look at Califa's Digital Information Forum   where I have placed several scanning articles and images of scanning stations.