Patent ID: 6501865
Filing Date: 2002-12-31
Classification: G06K,H04N

Abstract:
A dynamic thresholding module in combination with a contact image sensing module comprising:a comparator and a tracking low-pass filter comprising an analog circuit, said analog circuit processes an analog input video signal from said contact image sensing module and produces a two-level digital output, said dynamic thresholding module digitizes said input video signal by establishing a variable average background level for said input video signal, comparing said input video signal to said average background level in said comparator, and then generating an output signal that is of value one when said input video signal is from a light area of a scanned image, and said output signal is of value zero when said input video signal is from a dark area of a scanned image; and wherein said CIS contact image sensing module comprises a light source that emits light in the infrared range.