Patent ID: 8606012

Claim:
An image processing method for extracting line segment elements from a grayscale captured image, comprising the steps of: executing morphology processing by scanning an operator over an image according to said captured image in a plurality of directions and extracting linear elements from the scanned images in each direction; extracting an area of which contrast ratio is relatively high and an area of which contrast ratio is relatively low from the image on which said morphology processing is performed; and extracting the linear elements in said area of which contrast ratio is relatively low, connecting to said area of which contrast ratio is relatively high, as the line segment elements, and wherein said extracting line segment elements further comprises: a step of specifying an area of which contrast ratio of the image according to said captured image is possibly high; a step of extracting an area of which contrast ratio is relatively high and an area of which contrast ratio is relatively low for said specified area of said morphology-processed image; and a step of extracting linear elements in said area of which contrast ratio is relatively low, connecting to said area of which contrast ratio is relatively high, as the line segment elements, and wherein said step of extracting the area further comprises: a step of calculating a brightness frequency histogram in said specified area; and a step of extracting said area of which contrast ratio is relatively high and area of which contrast ratio is relatively low from said frequency histogram, and wherein said step of extracting said areas from said frequency histogram further comprises a step of extracting a mask area of which brightness level is relatively low as an area of which contrast ratio is relatively low, and a marker area of which brightness level is relatively high as an area of which contrast ratio is relatively high, from said frequency histogram.