Normalization method for eliminating false detections in side scan sonar images
First Claim
1. A method for eliminating false detections at the water column boundary in side scan sonar images consisting of a matrix of pixels, each pixel having a known greyness level, comprising the steps of:
- a. filtering each image by computing the median greylevel value of a pixel and its four adjacent pixels to produce a median image;
b. filtering said median image with a first linear filter to produce an edge image;
c. filtering said edge image with a second linear filter to produce an edge-smoothed image having a plurality of rows and columns;
d. detecting the edge by searching each row of said edge-smoothed image for the maximum greylevel;
e. defining a transition region between said detected edge and a preselected right boundary, said transition region having a plurality of rows and columns, and computing the average greylevels over the rows and columns in said transition region; and
f. normalizing the image by computing the image mean greyness level of each pixel in the image.
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Accused Products
Abstract
A method for eliminating false detections at the water column boundary in side scan sonar images is provided. Each image is filtered by computing the median greylevel value of a pixel and its four adjacent pixels to produce a median image. The median image is filtered with a first linear filter to produce an edge image. The edge image is then filtered with a second linear filter to produce an edge-smoothed image. The edge of the image is detected by searching each row of the edge-smoothed image for the maximum greylevel. A transition region is defined between the detected edge and a preselected right boundary and the average greylevels over the rows and columns in this transition region is computed. The sonar image is then normalized by computing the image mean grayness level of each pixel in the image.
44 Citations
16 Claims
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1. A method for eliminating false detections at the water column boundary in side scan sonar images consisting of a matrix of pixels, each pixel having a known greyness level, comprising the steps of:
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a. filtering each image by computing the median greylevel value of a pixel and its four adjacent pixels to produce a median image; b. filtering said median image with a first linear filter to produce an edge image; c. filtering said edge image with a second linear filter to produce an edge-smoothed image having a plurality of rows and columns; d. detecting the edge by searching each row of said edge-smoothed image for the maximum greylevel; e. defining a transition region between said detected edge and a preselected right boundary, said transition region having a plurality of rows and columns, and computing the average greylevels over the rows and columns in said transition region; and f. normalizing the image by computing the image mean greyness level of each pixel in the image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for eliminating false detections at the water column boundary in side scan sonar images consisting of a matrix of pixels, each pixel having a known greyness level, comprising:
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a. a median filter which computes the median greylevel value of a pixel and its four adjacent pixels and produces a median image; b. a first linear filter which receives said median image and produces an edge image; c. a second linear filter which receives said edge image and produces an edge-smoothed image having a plurality of rows and columns; d. edge detecting means which searches each row of said edge-smoothed image for the maximum greylevel; e. means for defining a transition region between said detected edge and a preselected right boundary, said transition region having a plurality of rows and columns and computing the average greylevels over the rows and columns in said transition region; and f. means for normalizing the image by computing the image mean greyness level of each pixel in the image. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification