Patent ID: 7630558

Claim:
A method of detecting lines in an image using a processor, the method comprising: using one or more square masks of size N by N pixels for detecting, using a processor, lines in one or more directions out of a first direction, a second direction transverse to the first direction, and third and fourth directions of diagonals with respect to said first and second directions; and detecting, using a processor, lines in a plurality of directions additional to said first to fourth directions using a plurality of additional square masks of size N by N pixels, each of said additional square masks having a line of N−2 central mask pixels and two sets of N−2 connected reference pixels placed at the extremities of the additional square masks, each set situated in a direction perpendicular to the direction of the line, wherein said central mask pixels are centered in the additional square masks, connected, and located in a discrete approximation of a straight line, and have a v_span or h_span equal to N−3, wherein N is the dimensions of the mask block, and v_span and h_span are the vertical and horizontal spans of the central mask pixels.