Patent ID: 7099509
Filing Date: 2006-08-29
Classification: G06T,H04N

Abstract:
1. A method for edge direction detection on a center line between two lines of an image having a plurality of lines of pixels, the method which comprises: selecting a pixel that is on the center line and defining the pixel as a selected pixel; calculating a vertical vector norm value from a plurality of adjoining pixels being on the two lines and being related to the selected pixel, the vertical vector norm value being associated with a vertical direction; using the vertical vector norm value to determine whether the selected pixel is in a non-vertical edge area; if the selected pixel is in the non-vertical edge area, then calculating two candidate edge directions based on a plurality of small-angle vector norm values each associated with a direction having a small-angle from the vertical direction; if the candidate edge direction is associated with a preferred direction, verifying that the candidate edge direction is consistent with an additional candidate edge direction; if every candidate edge direction that is associated with a preferred direction is consistent with the additional candidate edge direction, taking the additional candidate edge direction as a starting point for a direction fine tuning process including steps of: