Multiple measurement noise reducing system using space-variant filters
First Claim
1. For use in an imaging system, a method of reducing extraneous signals in a first processed image signal of an object representing a desired parameter derived from a plurality of measurements comprising the steps of:
- processing said plurality of measurements to provide a second processed image signal having greater signal-to-noise ratio than said first processed signal,low pass filtering said first processed image signal to reduce its noise,high pass filtering said second processed image signal, said high pass filtering being complementary to said low pass filtering;
varying the filter frequencies of said low pass filtering and said high pass filtering in response to presence of artifacts, andcombining said filtered first processed image and said filtered second processed image to provide an improved processed image signal.
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Abstract
Extraneous signals or artifacts are reduced in a multiple measurement noise reducing system such as an X-ray imaging system by processing a plurality of measurements to obtain a first image signal of an object representing a desired parameter such as a blood vessel, processing the plurality of measurements to provide a second image signal having increased signal-to-noise, low pass filtering the first image signal, high pass filtering the second image signal, and then combining the two filtered signals. The filter frequencies are varied in response to the presence of artifacts to minimize effects of the artifact on the combined signal.
46 Citations
13 Claims
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1. For use in an imaging system, a method of reducing extraneous signals in a first processed image signal of an object representing a desired parameter derived from a plurality of measurements comprising the steps of:
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processing said plurality of measurements to provide a second processed image signal having greater signal-to-noise ratio than said first processed signal, low pass filtering said first processed image signal to reduce its noise, high pass filtering said second processed image signal, said high pass filtering being complementary to said low pass filtering; varying the filter frequencies of said low pass filtering and said high pass filtering in response to presence of artifacts, and combining said filtered first processed image and said filtered second processed image to provide an improved processed image signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. In an imaging system, apparatus for reducing extraneous image signals in a processed image signal of an object representing a desired parameter derived from a plurality of measurements comprising:
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first processing means for processing said plurality of measurements and producing a first processed image signal representing said desired parameter, second processing means for processing said plurality of measurements and producing a second processed image signal having a greater signal-to-noise ratio than said first processed image signal, first filter means for receiving and low pass filtering said first processed image signal, second filter means for receiving and high pass filtering said second processed image signal, means for varying the filter bandwidths of said low pass filter means and said high pass filter means in response to presence of extraneous image signals, and means for combining said filtered first processed image signal and said filtered second processed image signal. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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Specification