Patent ID: 6690375
Filing Date: 2004-02-10
Classification: G06T

Abstract:
A line segment detector comprising:first weighted average means for calculating a weighted average of pixel values in a first detection window set in a first neighboring area of a target pixel in an input image; second weighted average means for calculating a weighted average of pixel values in a second detection window set in a second neighboring area point symmetrical with the first neighboring area with respect to the target pixel; differentiating means for calculating an absolute value of a difference between outputs from said first and second weighted average means; dot detecting means for calculating an average of absolute values of differential values between pixels in a direction of at least one of a vertical line, horizontal line, left-to-right downward slanting line, and left-to-right upward slanting line within a third detection window set in an area containing the target pixel: and comparing means for, if a subtraction result obtained by subtracting an output from said dot detecting means from an output from said differentiating means is larger than a predetermined threshold, determining that a portion near the target pixel is one of a vertical line image, horizontal line image, left-to-right downward slanting line image, and left-to-right upward slanting line image.