US5493619A — Normalization method for eliminating false detect…

Claim 1

Independent Claim 165 words

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.

Claim 2

Independent Claim 165 words

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.

Claim 3

Dependent Claim 27 words

The method of claim 1 wherein at least three iterations of said median filtering are performed before said median image is filtered by said first linear filter.

Claim 4

Dependent Claim 30 words

The method of claim 1 wherein segments are defined in the transition region between said detected edge and said right boundary and the average greylevel of the segments are computed.

Claim 5

Dependent Claim 18 words

The method of claim 3 wherein said image normalization is performed over three separate regions of said image.

Claim 6

Dependent Claim 36 words

The method of claim 4 wherein one of said three separate regions of said region is a water column region and the water column region of said image is normalized to have a constant greylevel mean.

Claim 7

Dependent Claim 34 words

The method of claim 4 wherein the greylevel of said segments between said water column boundary and said right boundary are normalized by a sliding mean that interpolates the greylevel means of said segments.

Claim 8

Dependent Claim 26 words

The method of claim 4 wherein the region to the right of said right boundary is normalized by a greylevel mean computed from a moving average.

Claim 9

Dependent Claim 17 words

The method of claim 7 wherein said moving average is computed using an odd number of columns.

Claim 10

Independent Claim 166 words

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: 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.

Claim 11

Independent Claim 166 words

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: 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.

Claim 12

Dependent Claim 27 words

The system of claim 9 wherein at least three iterations of said median filtering are performed before said median image is filtered by said first linear filter.

Claim 13

Dependent Claim 30 words

The system of claim 9 including means for defining segments in the transition region between said detected edge and said right boundary and computing the average greylevel of the segments.

Claim 14

Dependent Claim 18 words

The system of claim 11 wherein said image normalization is performed over three separate regions of said image.

Claim 15

Dependent Claim 36 words

The system of claim 12 wherein one of said three separate regions of said region is a water column region and the water column region of said image is normalized to have a constant greylevel mean.

Claim 16

Dependent Claim 34 words

The system of claim 12 wherein the greylevel of said segments between said water column boundary and said right boundary are normalized by a sliding mean that interpolates the greylevel means of said segments.

Claim 17

Dependent Claim 26 words

The system of claim 12 wherein the region to the right of said right boundary is normalized by a greylevel mean computed from a moving average.

Claim 18

Dependent Claim 17 words

The system of claim 15 wherein said moving average is computed using an odd number of columns.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-02-19	1999-08-21	2000-02-20	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-02-19	2003-08-21	2004-02-20	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-02-19	2007-08-21	2008-02-20	$7700.00	Window Closed / Lapsed

Normalization method for eliminating false detections in side scan sonar images

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