Patent ID: 7777921

Claim:
A method of controlling the velocity of a digital scanning unit associated with an image processing unit, the method comprising: capturing a color scan of a document in real time via an image sensing unit, wherein the document includes an edge between a white portion of the document and a colored portion of the document and the color scan of the document includes a plurality of pixels; determining whether a given pixel in the color scan is on the white portion, on the colored portion, or on the edge of the scanned document; where it is determined that a given pixel is on the edge, calculating a precise time when an edge transition occurred for each of three color signals; determining an elapsed time difference between a first and second color signal; using the elapsed time difference between the first and second color signals to calculate an instantaneous document velocity; comparing the instantaneous document velocity to a pre-determined document velocity to determine a difference between the instantaneous document velocity and the pre-determined document velocity; and adjusting the velocity of the digital scanning unit via a motion control system based upon the difference between the instantaneous document velocity and the pre-determined document velocity.