| 摘要 |
PURPOSE: To easily detect a straight line or arc which passes a known pixel position by extending and applying Hough transformation, used to detect the straight line in an image, to the detection of the arc. CONSTITUTION: A start point search means 2 scans an image memory in one direction to search for the pixel at the start point of the figure, and decides the pixel as a start point 8. When this position is regarded as an origin and other pixel positions constituting the figure are denoted as (x1 , y1 ) (i=1, 2...n, n: the number of pixels having pixel values other than 0), a characteristic curve accumulating means 3 accumulates the pixel values in a cell of a cumulative memory 4 satisfyingϕ=(xi cosω+yi sinω)/(x<2> i +y<2> i ) in a (ω,ϕ) space dispersed into plural cells. A peak detecting means 5 finds the peak of the accumulated value as an integration point (ω<0> ,ϕ0 ) and detects the figure being an arc which has its center r0 =1/2ϕ0 away from the origin in the direction of an angleω0 and has a radius r0 whenϕ0≠0 and detects the figure being a straight line which passes the origin and is in the direction of an angleω0 +π/2.
|
