US 5,963,661 AGranted

Method of detecting particle-like point in an image

AssigneeAdvantest Corporation

InventorsHaruo Kato, Kazuyuki Maruo

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Abstract

A particle-like point in an image is detected to detect a defect by directly processing an image of an object to be inspected. The image is first binarized, and the binarized image is scanned along an X-axis or a Y-axis, and a particle-like point in the image is approximated by a rectangular area. Information representative of the coordinates of the center of the rectangular area and the size of the rectangular area is outputted as information of the detected particle-like point.

Claims4

Dependent claims

A method of detecting a particle-like point in an image, comprising the steps of:

(a) binarizing an image with a predetermined threshold;
(b) scanning the binarized image in a first scanning direction parallel to an X-axis or a Y-axis, and detecting a pixel whose pixel value is 1 and which has not yet been registered as a particle-like point as a first pixel;
(c) scanning the binarized image from said first pixel in a second scanning direction perpendicular to said first scanning direction, detecting a pixel whose pixel value first becomes 0 as a second pixel, and if a pixel whose pixel value is 0 is not found and said binarized image has been scanned up to a frame thereof, detecting a pixel on said frame as a second pixel;
(d) scanning said binarized image in both of the scanning directions from a fifth pixel at a midpoint between said first pixel and said second pixel or a nearby point, on a straight line passing through said fifth pixel and parallel to said first scanning directions, and detecting pixels whose pixel values first become 0 as third and fourth pixels, and if a pixel whose pixel value is 0 is not found and said binarized image has been scanned up to a frame thereof, detecting pixels on said frame as third and fourth pixels, or scanning said binarized image on said straight line from a point spaced a predetermined distance from said fifth pixel in both of the scanning directions toward said fifth pixel, and detecting pixels whose pixel values first become 1 as third and fourth pixels, and if a point spaced said predetermined distance from said fifth pixel is not present in said binarized image, scanning said binarized image from a pixel at a point of intersection between said straight line and the frame of the binarized image toward said fifth pixel, and detecting pixels whose pixel values first become 1 as third and fourth pixels;
(e) outputting information representative of coordinates of a center of a rectangular area having said first, second, third, and fourth pixels on sides thereof and parallel to the X-axis and the Y-axis, setting the pixel values of all pixels in said rectangular area to 1, and registering all the pixels in said rectangular area as a particle-like point;
and
(i) repeating said steps (b), (c), (d), and (e) along said first and second scanning directions.

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Dependencies are inferred from the claim text.

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Abstract

A method of detecting a particle-like point in an image, comprising the steps of:

(a) binarizing an image with a predetermined threshold;
(b) scanning the binarized image in a first scanning direction parallel to an X-axis or a Y-axis, and detecting a pixel whose pixel value is 1 and which has not yet been registered as a particle-like point as a first pixel;
(c) scanning the binarized image from said first pixel in a second scanning direction perpendicular to said first scanning direction, detecting a pixel whose pixel value first becomes 0 as a second pixel, and if a pixel whose pixel value is 0 is not found and said binarized image has been scanned up to a frame thereof, detecting a pixel on said frame as a second pixel;
(d) scanning said binarized image in both of the scanning directions from a fifth pixel at a midpoint between said first pixel and said second pixel or a nearby point, on a straight line passing through said fifth pixel and parallel to said first scanning directions, and detecting pixels whose pixel values first become 0 as third and fourth pixels, and if a pixel whose pixel value is 0 is not found and said binarized image has been scanned up to a frame thereof, detecting pixels on said frame as third and fourth pixels, or scanning said binarized image on said straight line from a point spaced a predetermined distance from said fifth pixel in both of the scanning directions toward said fifth pixel, and detecting pixels whose pixel values first become 1 as third and fourth pixels, and if a point spaced said predetermined distance from said fifth pixel is not present in said binarized image, scanning said binarized image from a pixel at a point of intersection between said straight line and the frame of the binarized image toward said fifth pixel, and detecting pixels whose pixel values first become 1 as third and fourth pixels;
(e) outputting information representative of coordinates of a center of a rectangular area having said first, second, third, and fourth pixels on sides thereof and parallel to the X-axis and the Y-axis, setting the pixel values of all pixels in said rectangular area to 1, and registering all the pixels in said rectangular area as a particle-like point;
and
(i) repeating said steps (b), (c), (d), and (e) along said first and second scanning directions.

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