1. A method for detecting straight line information, comprising steps of: (A) inputting an image with extracted edge; (B) designating pixels of the image into block-wise units each comprising a predetermined number of pixels; (C) calculating votes of representative pixels per designated block; (D) calculating votes of rest pixels per block, using the votes of the representative pixels per block; (E) counting accumulated frequencies per vote, using the votes calculated at steps (C) and (D); and (F) detecting straight line information based on the accumulated frequency information that exceeds a threshold, wherein said calculating votes of rest pixels per block calculates said votes of rest pixels per block by reducing a fraction term using a trigonometrical function according to a relative coordinate of rest pixels with respect to the representative pixels.