Noise reduction method and apparatus for medical ultrasound
First Claim
1. A method of processing ultrasound image data to reduce acoustic speckle noise and enhance selected portions of the image, the image being formed from a plurality of pixels arranged in a spatial array and said data representing an intensity level in each pixel, the method comprising weighting the data representative of preselected ones of less than all of the pixels of an asymmetric portion of said spatial array with predetermined coefficient values, said preselected pixels and said coefficient values being selected to enhance the leading edges of spots in the image which have a size greater than a predetermined size corresponding to an average size of acoustic speckle and which have a predetermined location in the asymmetric portion;
- combining the weighted data to produce a transformed intensity value;
repeating said weighting and said combining for a plurality of different asymmetric portions of the spatial array;
forming another array of pixels by using each transformed intensity value as a value of a pixel of said other array which corresponds to a central pixel of the corresponding asymmetric portion; and
displaying said other array as an image.
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Abstract
Ultrasonic images are enhanced by applying to the images asymmetric balanced gradient operators or masks which are formed to produce values which are maximized at the edges of spots having a predetermined size and location relative to the mask, which spots have a high likelihood of being specular targets. The gradient operators are further formed to produce minimum values for smaller spots corresponding to acoustic speckle. In the resultant image, the edges of specular targets are enhanced and acoustic speckle is substantially eliminated. Ultrasonic images may be processed in real time with the gradient operators in either an image processing computer or in a hardware pipeline processor.
96 Citations
22 Claims
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1. A method of processing ultrasound image data to reduce acoustic speckle noise and enhance selected portions of the image, the image being formed from a plurality of pixels arranged in a spatial array and said data representing an intensity level in each pixel, the method comprising weighting the data representative of preselected ones of less than all of the pixels of an asymmetric portion of said spatial array with predetermined coefficient values, said preselected pixels and said coefficient values being selected to enhance the leading edges of spots in the image which have a size greater than a predetermined size corresponding to an average size of acoustic speckle and which have a predetermined location in the asymmetric portion;
- combining the weighted data to produce a transformed intensity value;
repeating said weighting and said combining for a plurality of different asymmetric portions of the spatial array;
forming another array of pixels by using each transformed intensity value as a value of a pixel of said other array which corresponds to a central pixel of the corresponding asymmetric portion; and
displaying said other array as an image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- combining the weighted data to produce a transformed intensity value;
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9. A method of processing ultrasound image data to reduce acoustic speckle noise and enhance selected portions of the image, the image being formed from a plurality of pixels arranged in a spatial array and said data representing an intensity level in each pixel, the method comprising applying to the data representative of preselected pixels comprising less than all of the pixels of an asymmetric portion of the spatial array a gradient operator, the operator having a plurality of elements, each element corresponding to a different pixel of the asymmetric portion and preselected ones of the elements of the operator corresponding to said preselected pixels being assigned coefficient values, said applying comprising forming a weighted sum of the product of the coefficient values and intensity values of corresponding pixels of the asymmetric portion to produce a new intensity value representative of an intensity gradient in a predetermined area of the asymmetric portion;
- the preselected pixels and the coefficient values being selected to enhance the intensity of spots in the image which are greater than a predetermined size and to minimize the intensity of other spots which are less than the predetermined size;
repeating said applying for a plurality of asymmetric portions;
forming another spatial array of pixels using the new intensity values; and
displaying said other array as an image. - View Dependent Claims (10, 11, 12, 13, 14)
- the preselected pixels and the coefficient values being selected to enhance the intensity of spots in the image which are greater than a predetermined size and to minimize the intensity of other spots which are less than the predetermined size;
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15. 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. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
- 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;
Specification