The University of Illinois Map and Geography Library maintains a collection of approximately 60,000 individual prints of historical aerial photography that were acquired during the years 1936-1941, for which there are no remaining negatives. Because of high use by library patrons, the collection is deteriorating and a method of preservation is needed. A pilot study was conducted to evaluate the...

A lthough real world signals are analog, it is often desirable to convert them into the digital domain .using an analog to digital converter (ADC). Motivating designers to apply this conversion is the efficient transmission and storage of digital signals. Digital representation of an audio signal, for example, allows CD players to achieve virtually error free storage using optical disks [l]. In...