Patent ID: 6678411
Filing Date: 2004-01-13
Classification: G06F,G06K

Abstract:
A method of characterizing shape content of an optical image, comprising:transforming the image from spatial domain to Fourier domain by passing light energy that comprises the image through a Fourier transform lens to create an optical Fourier transform pattern of the light energy in a focal plane of the lens positioned on an optic axis at a focal distance from the lens; spatially filtering the Fourier transform pattern in the focal plane to pass light energy from only a discrete portion of the Fourier transform pattern positioned radially outward from, and at a discrete angular orientation about, the optic axis; projecting the filtered light energy from said discrete portion of the Fourier transform pattern back into a spatial domain optical image that corresponds to a portion of the shape content of the optical image; detecting intensities of the light energy at multiple, divers locations in the spatial domain optical image of said portion that corresponds to the shape content; recording the intensities of light energy detected at said multiple, divers locations in the spatial domain optical image that corresponds to said portion of the shape content; and repeating said spatially filtering of the Fourier transform pattern, projecting the light energy, detecting intensities, and recording intensities, but for multiple other discrete portions of the Fourier transform pattern positioned radially outward from, and at different angular orientations about, the optic axis.