Method of erasing repeated patterns and pattern defect inspection device
First Claim
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1. A method of erasing repeated patterns in a dark/light image obtained by image pickup of a subject of inspection, when identifying defects present in a repeated pattern in the subject of inspection, comprising:
- detecting a reference pixel in the obtained image;
assigning a comparison pixel at a predetermined distance from the reference pixel, the distance being determined in accordance with the pattern pitch of the repeated patterns in the dark/light image;
obtaining a plurality of density differences between said reference pixel and each of said comparison pixels, wherein when a density of the reference pixel is larger than a density of the comparison pixel, a density difference is positive, and when the density of the reference pixel is smaller than the density of the comparison pixel, the density difference is negative;
determining the density difference that is closest to 0 as a specific density difference; and
applying said specific density difference to a reference density of the image, thereby erasing the repeated patterns in the dark/light image to identify defects in a pattern-erased image.
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Abstract
An image of a subject of inspection is picked up, and this image is demarcated into a plurality of areas. Density differences are found between reference pixels and a plurality of comparison pixels in the demarcated areas, and a density difference that is closest to 0 is determined as a specific density difference. The specific density difference is then applied to the reference density in the image of the subject, whereby repeated patterns in the image are erased.
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6 Claims
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1. A method of erasing repeated patterns in a dark/light image obtained by image pickup of a subject of inspection, when identifying defects present in a repeated pattern in the subject of inspection, comprising:
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detecting a reference pixel in the obtained image;
assigning a comparison pixel at a predetermined distance from the reference pixel, the distance being determined in accordance with the pattern pitch of the repeated patterns in the dark/light image;
obtaining a plurality of density differences between said reference pixel and each of said comparison pixels, wherein when a density of the reference pixel is larger than a density of the comparison pixel, a density difference is positive, and when the density of the reference pixel is smaller than the density of the comparison pixel, the density difference is negative;
determining the density difference that is closest to 0 as a specific density difference; and
applying said specific density difference to a reference density of the image, thereby erasing the repeated patterns in the dark/light image to identify defects in a pattern-erased image. - View Dependent Claims (2, 3, 4)
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5. A pattern defect inspection device comprising:
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an image pickup element that picks up an image of a subject of inspection;
a processing device that detects pattern defects by storing and processing dark/light image data obtained by image pickup of the inspection subject, wherein the processing device detects a reference pixel in the obtained image, assigns a comparison pixel at a predetermined distance from the reference pixel, the distance being determined in accordance with the pattern pitch of the repeated patterns in the dark/light image, and obtains a plurality of density differences between said reference pixel and each of said comparison pixels, wherein when a density of the reference pixel is larger than a density of the comparison pixel, a density difference is positive, and when the density of the reference pixel is smaller than the density of the comparison pixel, the density difference is negative;
a unit for determining a density difference that is closest to 0 as a specific density difference; and
a unit for applying the specific density difference to a reference density of the image and generating a pattern-erased image to identify defects in the pattern-erased image. - View Dependent Claims (6)
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Specification