Adaptive persistence processing
First Claim
1. An adaptive persistence filter in an ultrasound imaging system, the filter comprising:
- a first stage filter selected from the group of;
recursive and nonrecursive filters comprising a first input and a first output and responsive to a substantially constant filtering coefficient; and
a second stage filter selected from the group of;
recursive and nonrecursive filters operatively connected to the first output and responsive to a dynamic filtering coefficient.
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Abstract
The invention provides a method and system for adaptive persistence processing in an ultrasound imaging system. Acoustic signals are temporally filtered using an adaptive persistence filter, having a recursive stage followed by a nonrecursive stage. A set of filtering coefficients for each stage are supplied by a look-up table in a memory, addressed or indexed in response to a plurality of input or output pixel values. The look-up table may therefore embody any selected function of its input variables. The input variables for the look-up table function are a current input pixel value Xn and a previous intermediate pixel value Wn-1, and the function embodied by the look-up table includes a relative first difference function for selecting a filter coefficient. A recursive filtering coefficient α is held constant over time, while a nonrecursive filtering coefficient γis adjusted dynamically in response to the current input pixel value Xn and the previous intermediate pixel value Wn-1. The non-recursive stage filter has a frequency response that attenuates higher frequency components without attenuating a broad range of lower frequency components, relative to the recursive stage frequency response. The step response or settling time of the non-recursive stage filter always spans one frame interval, independent of the nonrecursive filtering coefficient, while the step response or settling time for the recursive stage filter is generally longer and is dependent on the recursive filtering coefficient.
65 Citations
50 Claims
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1. An adaptive persistence filter in an ultrasound imaging system, the filter comprising:
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a first stage filter selected from the group of;
recursive and nonrecursive filters comprising a first input and a first output and responsive to a substantially constant filtering coefficient; anda second stage filter selected from the group of;
recursive and nonrecursive filters operatively connected to the first output and responsive to a dynamic filtering coefficient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of adaptive persistence filtering in an ultrasound imaging system, the method comprising the steps of:
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receiving an input signal; filtering the input signal with a first stage filter selected from the group of;
recursive and nonrecursive filters responsive to a substantially constant filtering coefficient; andfiltering an output signal from the first stage filter with a second stage filter selected from the group of;
recursive and nonrecursive filters responsive to a dynamic filtering coefficient. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. An adaptive persistence filter in an ultrasound imaging system, the filter comprising:
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a first stage filter selected from the group of;
recursive and nonrecursive filters comprising a first input and a first output and responsive to a first filtering coefficient;a second stage filter selected from the group of;
recursive and nonrecursive filters operatively connected to the first output and responsive to a dynamic filtering coefficient; andthe dynamic filtering coefficient responsive to at least two signals selected from the group of signals at;
the first input, the first output, and a delayed first output. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A method of adaptive persistence filtering in an ultrasound imaging system, the method comprising the steps of:
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receiving an input signal; filtering said input signal with a first stage filter selected from the group of;
recursive and nonrecursive filters responsive to a first filtering coefficient;filtering an output signal from the first stage filter with a second stage filter selected from the group of;
recursive and nonrecursive filters responsive to a dynamic filtering coefficient; andadjusting the dynamic filtering coefficient in response to at least two signals selected from the group of;
the input signal, the output signal and a delayed output signal. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50)
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Specification