Noise reduction method and apparatus for medical ultrasound

Claim 3

The method of claim 1, wherein said weighting comprises multiplying the intensity values of pixels in a lower central area of said asymmetric portion by positive integers and multiplying the intensity values of pixels in opposite upper corners of said asymmetric portion by negative integers, and wherein said combining comprises summing the results of said multiplications.

Claim 4

The method of claim 2, wherein said integers all have an absolute value of 1.

Claim 5

The method of claim 2, wherein the predetermined size of said spots is at least equivalent to the size of an array of 3×2 pixels, and said predetermined location comprises said lower central area.

Claim 6

The method of claim 1, wherein said preselected pixels and said predetermined coefficients are selected such that the transformed intensity value is a function of a bi-angular gradient of intensity values of a spot in a lower central area of the asymmetric portion.

Claim 7

The method of claim 5, wherein said asymmetric portion comprises a 3×7 array.

Claim 8

The method of claim 1, wherein said repeating comprises selecting the asymmetric portions such that successive portions overlap and such that the entire spatial array of pixels is covered.

Claim 9

The method of claim 1, wherein said image is an ultrasonic image of a portion of a human body, and said image data is in polar format.

Claim 12

The method of claim 9, wherein said gradient operator comprises a balanced operator formed to produce a biangular gradient value that is maximized for spots of a predetermined size located in said predetermined area of the asymmetric portion.

Claim 13

The method of claim 10, wherein said gradient operator is formed such that the new intensity values enhance the edges of said spots.

Claim 14

The method of claim 9, wherein said asymmetric portion comprises a 3×7 array of pixels and said gradient operator comprises a 3×7 mask, and said preselected elements comprise a first group of elements located in a lower central portion of the mask, and second and third groups of elements located in opposite upper corners of the mask.

Claim 15

The method of claim 12, wherein said first group of elements has positive coefficient values and said second and third groups have negative coefficient values.

Claim 16

The method of claim 9, wherein said repeating comprises successively applying the gradient operator to a plurality of overlapping asymmetric portions until the entire image is covered.

Claim 17

Apparatus for processing ultrasound image data to reduce acoustic speckle noise and enhance selected portions of the image, the image being formed by pluralities of pixels arranged in a plurality of lines and the image data representing the intensity level in each of the pixels, the apparatus comprising means for receiving successive data corresponding to successive pixels; means for applying to the data an asymmetrical operator for enhancing spots in the image which correspond to specular targets and for eliminating from the image spots which correspond to acoustic speckle, the applying means comprising first delay means connected to the receiving means for delaying said data by an interval corresponding to one line; second delay means for delaying the data from the first delay means by another interval corresponding to one line; third delay means connected to the receiving means for delaying the data by first predetermined pixel intervals to produce a first set of delayed pixel data; fourth delay means for delaying the data from the first delay means by second predetermined pixel intervals to produce a second set of delayed pixel data; fifth delay means for delaying the data from the second delay means by third predetermined pixel intervals to produce a third set of delayed pixel data; the third, fourth and fifth delay means being selected such that the first, second and third sets of delayed pixel data represent less than all of the pixels of an asymmetrical array of pixels which corresponds to said asymmetrical operator; means for combining successive first, second, and third sets of delayed pixel data to produce corresponding successive new intensity values; and means connected to the combining means for forming a new line of pixels from said new intensity values.

Claim 18

Apparatus for processing ultrasound image data to reduce acoustic speckle noise and enhance selected portions of the image, the image being formed by pluralities of pixels arranged in a plurality of lines and the image data representing the intensity level in each of the pixels, the apparatus comprising means for receiving successive data corresponding to successive pixels; means for applying to the data an asymmetrical operator for enhancing spots in the image which correspond to specular targets and for eliminating from the image spots which correspond to acoustic speckle, the applying means comprising first delay means connected to the receiving means for delaying said data by an interval corresponding to one line; second delay means for delaying the data from the first delay means by another interval corresponding to one line; third delay means connected to the receiving means for delaying the data by first predetermined pixel intervals to produce a first set of delayed pixel data; fourth delay means for delaying the data from the first delay means by second predetermined pixel intervals to produce a second set of delayed pixel data; fifth delay means for delaying the data from the second delay means by third predetermined pixel intervals to produce a third set of delayed pixel data; the third, fourth and fifth delay means being selected such that the first, second and third sets of delayed pixel data represent less than all of the pixels of an asymmetrical array of pixels which corresponds to said asymmetrical operator; means for combining successive first, second, and third sets of delayed pixel data to produce corresponding successive new intensity values; and means connected to the combining means for forming a new line of pixels from said new intensity values.

Claim 19

The apparatus of claim 15, wherein said first set of delayed pixel data comprises data corresponding to a pixel on a current line which is delayed by four pixel intervals, said second set of delayed pixel data comprises data corresponding to pixels on a previous line delayed by one, three, four, five and seven pixel intervals, and said third set of delayed pixel data comprises data corresponding to pixels on a second previous line delayed by one and seven pixel intervals.

Claim 20

The apparatus of claim 16, wherein said combining means comprises means for summing the data corresponding to the pixel on the current line and the data corresponding to the pixel on the previous line delayed by four pixel intervals to produce a result, and means for subtracting from such result the sum of the remaining data of said second and third sets to produce said new intensity value.

Claim 21

The method of claim 15, further comprising scaling said new intensity values to a predetermined range of grey level intensity values.

Claim 22

The apparatus of claim 15, further comprising means for forming a plurality of said new lines of pixels to form a processed image, and means for displaying said processed image on a video display.

Claim 23

The apparatus of claim 15, wherein said first and second delay means each comprise random access memories, and said third, fourth and fifth delay means each comprise shift registers.

Claim 24

The apparatus of claim 15, wherein said first, second and third sets of delayed pixel data are selected such that the new intensity value produced by the combining means is maximized at the edges of a spot on said image which is larger than a predetermined size.

Claim 25

The apparatus of claim 21, wherein said sets of delayed pixel data are selected such that the new intensity value corresponds to a biangular gradient of intensity values in a predetermined area of the image.