el Amor, , and 2007 Color Elefante, . A 2008 exhibition titled "Scanner as Camera" at Washington and Lee University in Lexington, Virginia drew eight artists from across the United States whose subjects ranged from scanned and digitally manipulated historic ambrotype and tintype photographs and drawings to birds and insects found by the artist. Capture process Scanners differ significantly from digital camera in many areas. First, the optical resolution of a flatbed scanner can exceed 5000 pixels per inch (200 pixels per mm). Even at a relatively low resolution of 1200 pixels per inch (47 p/mm) a letter sized image would be 134 megapixels in size. The depth of field of most scanners is very limited, usually no more than half an inch (12 mm), but the built-in light source provides excellent sharpness, color saturation, and unique shadow effects. The time it takes the scanning head to traverse the bed means that scanners can only be used to capture still objects, and common items used are flowers, leaves, and other suitable "still life" subjects. Equipment Using a flatbed scanner to scan items other than paper documents exceeds the original purpose of the scanner, so special care must be taken with the process. The bed of the scanner is typically made of glass, and care needs to be taken that the glass not be scratched or cracked when placing or removing items on the bed. Since the items to be captured are often placed directly on the bed, dust and other particles will often land on the glass, and care must be taken to keep the glass clean. Scanners will also hold only a limited amount of weight, and items that may damage the scanner, such a liquids or items that might scratch the glass, should be placed on a plastic barrier to protect the bed. Alternatively, picture frame glass cut a few inches larger than the scanner housing will protect the platen and the device from weeping botanical specimens, paints, melting ice, burning leaves or whatever the challenge. There are only two standard flatbed scanner sizes: "document" (slightly larger than a sheet of letterhead size paper and "large format" approximately the size of two sheets of paper side-by-side. Many scanners advertise two resolutions, an optical resolution and a higher resolution that is achieved by interpolation. A higher optical resolution is desirable, since that captures more data, while interpolation can actually