Method and system for enhancing image quality
AssigneeHermes Microvision, Inc.
InventorsChiyan Kuan, Joe Wang, Van-Duc Nguyen
Life of this patent
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Abstract
This invention relates to methods and systems for enhance the signal-to-noise ratio of an image scanned by a charged particle beam. In an embodiment, a sequence of grayscales of a pixel is recorded first, extreme values of the sequence of grayscales are then identified and removed, and the remained grayscales are used to determine a nominated grayscale of the pixel.
Claims26
A method for enhancing image quality, comprising:
- repeatedly scanning a pixel by a charged particle beam;
- recording a sequence of grayscales of the pixel scanned by the charged particle beam;
- removing extreme values from the sequence of grayscales;
- and
- determining a nominated grey level of the pixel from remained grayscales in order to enhance the image quality,
- wherein the extreme grayscales of each pixel include less than a lower limit (LL) and more than a upper limit (UL) of grayscales of each pixel, in which the lower limit is μ minus 0.67σ, the upper limit is μ plus 0.676σ, and μ and σ respectively stand for the mean and the standard deviation of the grayscales of each pixel.
A system for enhancing image quality, comprising:
- a charged particle beam repeatedly scanning a pixel;
- means for recording a sequence of grayscales of the pixel scanned by the charged particle beam;
- means for removing extreme values from the sequence of grayscales;
- and
- means for calculating an average or a median of remained grayscales to obtain an nominated grayscale of the pixel in order to enhance the image quality,
- wherein the extreme grayscales of each pixel include less than a lower limit (LL) and more than a upper limit (UL) of grayscales of each pixel, in which the lower limit is μ minus 0.67σ, the upper limit is μ plus 0.67σ, and μ and σ respectively stand for the mean and the standard deviation of the grayscales of each pixel.
A method for enhancing image quality, comprising:
- scanning a specimen to obtain a plurality of frames by using a charged particle beam;
- removing extreme grayscales of each pixel of the plurality of frames;
- averaging remained grayscales of each pixel of the plurality of frames to obtain a scanned image of the specimen in order to enhance the image quality,
- wherein the extreme grayscales of each pixel include less than a lower limit (LL) and more than a upper limit (UL) of grayscales of each pixel, in which the lower limit is μ minus 0.67σ, the upper limit is μ plus 0.67σ, and μ and σ respectively stand for the mean and the standard deviation of the grayscales of each pixel.
A non-transitory computer readable medium encoded with a computer program for enhancing image quality of an inspection system, comprising the steps of:
- recording a sequence of grayscales of a pixel scanned by a charged particle beam;
- removing extreme values from the sequence of grayscales;
- and
- determining a nominated grey level of the pixel from remained grayscales in order to enhance the image quality,
- wherein the extreme grayscales of each pixel include less than a lower limit (LL) and more than a upper limit (UL) of grayscales of each pixel, in which the lower limit is μ minus 0.67σ, the upper limit is μ plus 0.67σ, and μ and σ respectively stand for the mean and the standard deviation of the grayscales of each pixel.
Dependencies are inferred from the claim text.