Color scanner using both variable led exposure time and photo detector output compensation

摘要

The present invention provides a combination of first providing a coarse adjustment by varying the emitter power and duration of the emitter/detector exposure time, and then providing a fine adjustment by storing a correction value for each photodetector element. The adjustment for each photodetector corrects not only for the range, but also for the offset, providing two correction values. In a preferred embodiment, the low and high voltage reference levels for an analog to digital converter are adjusted and stored for each photodetector for each color.