| 摘要 |
PURPOSE:To reduce the quantity of calculation for an autocorrelation function, etc., in a local area by projecting the light-shade degree of picture elements in the local area on segments which have various predetermined angles and are on the same plane with the picture elements. CONSTITUTION:The picture elements in a small area (s) in an image to be processed are projected on a straight line L which has an angle theta to an X axis. Namely, values of picture elements on a straight line l which has an angle theta+pi/2 and is at distance (t) from a center (o) are summed up and stored in an address (t,theta) of an image memory repeatedly while (t) is varied from -R to +R and theta is varied from (o) to pi. When the contents of the address (t,theta) are denoted as A(t,theta), a two-dimensional spatial frequency power spectrum P(k,theta) regarding the index (t) is obtained by squaring the absolute value of a linear discrete Fourier transform F(k,theta) regarding the index (t) of the A(t,theta).
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