Image registration using fourier phase matching
First Claim
1. A method for image frame registration, comprising the steps of:
- storing first and second image frames of pixel values;
transforming said first and second image frames into first and second frequency domain representations respectively using a two-dimensional Fast Fourier transformation;
processing said first and second frequency domain representations to determine a rotation parameter and a scaling parameter needed for said first image frame to be in registration with said second image frame;
rotating said first image frame in accordance with said rotation parameter; and
scaling said first image frame in accordance with said scaling parameter.
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Abstract
A method and an apparatus for registering frames of imaging data using Fourier phase matching. Successive image frames of pixel data are processed using an image registration algorithm. Either image frames or the frames after edge detection are transformed into polar-logarithmic coordinates in the frequency domain and the phases of the Fourier transform of the resulting image representations, after inverse Fast Fourier transformation, are matched. The coordinates at the maximum phase difference are used to determine the scaling and rotation parameters needed for image frame registration. The frequency domain representation of one of the image frames is then scaled and rotated using an anti-aliasing algorithm in accordance with those parameters. The phase of the result is matched with the phase of the frequency domain representation of the other image frame to determine the translation parameters needed for image frame registration.
203 Citations
29 Claims
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1. A method for image frame registration, comprising the steps of:
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storing first and second image frames of pixel values;
transforming said first and second image frames into first and second frequency domain representations respectively using a two-dimensional Fast Fourier transformation;
processing said first and second frequency domain representations to determine a rotation parameter and a scaling parameter needed for said first image frame to be in registration with said second image frame;
rotating said first image frame in accordance with said rotation parameter; and
scaling said first image frame in accordance with said scaling parameter. - View Dependent Claims (2, 3, 4, 5)
rotating and scaling said first frequency domain representation in accordance with shear transformations that are a function of said rotation parameter and a scaling transformation that is a function of said rotation parameter and said scaling parameter;
processing said rotated and scaled first frequency domain representation and said second frequency domain representation to determine first and second translation parameters; and
translating said first image frame in first and second directions in accordance with said first and second translation parameters respectively.
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3. The method as recited in claim 1, wherein said processing step for determining rotation and scaling parameters comprises the steps of:
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transforming the magnitudes of said first and second frequency domain representations into polar coordinates in the frequency domain to form first and second polar-logarithmic representations respectively;
transforming said first and second polar-logarithmic representations into first and second Fourier-transformed polar-logarithmic representations respectively using a two-dimensional Fast Fourier transformation;
extracting the phase from each of said first and second Fourier-transformed polar-logarithmic representations;
transforming a phase difference between said phases of said first and second Fourier-transformed polar-logarithmic representations using a two-dimensional inverse Fast Fourier transformation;
detecting a maximum in said phase difference;
determining said rotation parameter as a function of a first coordinate of said maximum; and
determining said scaling parameter as a function of a second coordinate of said maximum.
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4. The method as recited in claim 2, wherein said processing step for determining translation parameters comprises the steps of:
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extracting the phase from each of said rotated and scaled first frequency domain representation and said second frequency domain representation;
transforming a phase difference between said phase of said rotated and scaled first frequency domain representation and said phase of said second frequency domain representation using a two-dimensional inverse Fast Fourier transformation; and
detecting a maximum in said phase difference, said first and second translation parameters being first and second coordinates of said maximum respectively.
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5. The method as recited in claim 4, further comprising the step of comparing said maximum phase difference to a predetermined threshold.
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6. A system for image frame registration comprising:
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a memory for storing first and second image frames of pixel values; and
an image registration processor programmed to perform the steps of;
(a) transforming said first and second image frames into first and second frequency domain representations respectively using a two-dimensional Fast Fourier transformation;
(b) processing said first and second frequency domain representations to determine a rotation parameter and a scaling parameter needed for said first image frame to be in registration with said second image frame;
(c) rotating said first image frame in accordance with said rotation parameter; and
(d) scaling said first image frame in accordance with said scaling parameter. - View Dependent Claims (7)
(a) rotating and scaling said first frequency domain representation in accordance with shear transformations that are a function of said rotation parameter and a scaling transformation that is a function of said rotation parameter and said scaling parameter;
(b) processing said rotated and scaled first frequency domain representation and said second frequency domain representation to determine first and second translation parameters;
(c) translating said first image frame in first and second directions in accordance with said first and second translation parameters respectively; and
(d) storing said rotated, scaled and translated first image frame in said memory.
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8. An ultrasound imaging system comprising:
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an ultrasound transducer array comprising a multiplicity of transducer elements;
a transmit beamformer for pulsing selected transducer elements during first and second series of transmit firings constituting first and second scans respectively;
a receive beamformer coupled to selected transducer elements of said transducer array for acquiring a respective receive signal subsequent to each transmit firing;
a signal processor programmed to form first and second sets of processed signals from said receive signals for said first and second scans respectively;
a converter for converting said first and second sets of processed signals into said first and second image frames respectively;
a memory for storing first and second image frames of pixel values; and
a computer programmed to rotate, scale and translate said second image frame to be in registration with said first image frame based on phase matching of frequency domain representations derived from said first and second image frames, and produce a final image frame of pixel data which is a function of said first image frame and said rotated, scaled and translated second image frame; and
a display device comprising a multiplicity of pixels for displaying said final image frame.
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9. An ultrasound imaging system comprising:
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a memory for storing first and second image frames of ultrasound pixel data;
a computer programmed to rotate, scale and translate said second image frame to be in registration with said first image frame based on phase matching of frequency domain representations derived from said first and second image frames, and produce a final image frame of pixel data which is a function of said first image frame and said rotated, scaled and translated second image frame; and
a display device comprising a multiplicity of pixels for displaying said final image frame.
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10. A method for ultrasound imaging comprising the steps of:
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storing first and second image frames of ultrasound imaging data;
rotating, scaling and translating said second image frame to be in registration with said first image frame based on phase matching of frequency domain representations derived from said first and second image frames;
producing a final image frame of pixel data which is a function of said first image frame and said rotated, scaled and translated second image frame; and
displaying said final image frame. - View Dependent Claims (11, 12)
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13. An imaging system comprising:
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a memory for storing first and second image frames of pixel values;
a computer programmed to perform the steps of;
(a) transforming said first and second image frames into first and second frequency domain representations respectively using a two-dimensional Fast Fourier transformation;
(b) processing said first and second frequency domain representations to determine a rotation parameter and a scaling parameter needed for said first image frame to be in registration with said second image frame;
(c) rotating said first image frame in accordance with said rotation parameter;
(d) scaling said first image frame in accordance with said scaling parameter; and
(e) producing a final image frame of pixel data which is a function of said rotated and scaled first image frame and said second image frame; and
a display device comprising a multiplicity of pixels for displaying said final image frame. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
(a) rotating and scaling said first frequency domain representation in accordance with shear transformations that are a function of said rotation parameter and a scaling transformation that is a function of said rotation parameter and said scaling parameter;
(b) processing said rotated and scaled first frequency domain representation and said second frequency domain representation to determine first and second translation parameters; and
(c) translating said first image frame in first and, second directions in accordance with said first and second translation parameters respectively, wherein said final image frame of pixel data is a function of said rotated, scaled and translated first image frame and said second image frame.
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15. The imaging system as recited in claim 13, wherein said processing step to determine rotation and scaling parameters comprises the following steps:
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(a) transforming the magnitudes of said first and second frequency domain representations into polar coordinates in the frequency domain to form first and second polar-logarithmic representations respectively;
(b) transforming said first and second polar-logarithmic representations into first and second Fourier-transformed polar-logarithmic representations respectively using a two-dimensional Fast Fourier transformation;
(c) extracting the phase from each of said first and second Fourier-transformed polar-logarithmic representations;
(d) transforming a phase difference between said phases of said first and second Fourier-transformed polar-logarithmic representations using a two-dimensional inverse Fast Fourier transformation;
(e) detecting a maximum in said phase difference;
(f) determining said rotation parameter as a function of a first coordinate of said maximum; and
(g) determining said scaling parameter as a function of a second coordinate of said maximum.
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16. The imaging system as recited in claim 14, wherein said processing step to determine translation parameters comprises the following steps:
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(a) extracting the phase from each of said rotated and scaled first frequency domain representation and said second frequency domain representation;
(b) transforming a phase difference between said phase of said rotated and scaled first frequency domain representation and said phase of said second frequency domain representation using a two-dimensional inverse Fast Fourier transformation; and
(c) detecting a maximum in said phase difference, said first and second translation parameters being first and second coordinates of said maximum respectively.
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17. The imaging system as recited in claim 16, wherein said computer is further programmed to perform the step of comparing said maximum phase difference to a predetermined threshold.
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18. The imaging system as recited in claim 14, wherein said final image frame of pixel data is produced by spatially compounding a set of image frames including at least said first image frame after said rotating, scaling and translating steps and said second image frame.
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19. The imaging system as recited in claim 15, wherein said final image frame of pixel data is produced by reconstructing a three-dimensional image from a set of image frames including at least said first image frame after said rotating, scaling and translating steps and said second image frame.
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20. The imaging system as recited in claim 14, wherein said transforming step comprises the steps of combining said first and second image frames in an even location-odd location separation and then transforming said combined image frames in a single two-dimensional Fast Fourier transformation.
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21. The imaging system as recited in claim 14, further comprising:
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an ultrasound transducer array comprising a multiplicity of transducer elements;
a transmit beamformer for pulsing selected transducer elements during first and second series of transmit firings constituting first and second scans respectively;
a receive beamformer coupled to selected transducer elements of said transducer array for acquiring a respective receive signal subsequent to each transmit firing;
a signal processor programmed to form first and second sets of processed signals from said receive signals for said first and second scans respectively; and
a converter for converting said first and second sets of processed signals into said first and second image frames respectively.
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22. An imaging system comprising:
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a memory for storing first and second image frames of pixel values;
means for transforming said first and second image frames into first and second frequency domain representations respectively using a two-dimensional Fast Fourier transformation;
means for processing said first and second frequency domain representations to determine a rotation parameter and a scaling parameter needed for said first image frame to be in registration with said second image frame;
means for rotating said first image frame in accordance with said rotation parameter;
means for scaling said first image frame in accordance with said scaling parameter; and
means for producing a final image frame of pixel data which is a function of said rotated and scaled first image frame and said second image frame; and
a display device comprising a multiplicity of pixels for displaying said final image frame. - View Dependent Claims (23, 24, 25, 26, 27)
means for rotating and scaling said first frequency domain representation in accordance with shear transformations that are a function of said rotation parameter and a scaling transformation that is a function of said rotation parameter and said scaling parameter;
means for processing said rotated and scaled first frequency domain representation and said second frequency domain representation to determine first and second translation parameters; and
means for translating said first image frame in first and second directions in accordance with said first and second translation parameters respectively, wherein said final image frame of pixel data is a function of said rotated, scaled and translated first image frame and said second image frame.
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24. The imaging system as recited in claim 22, wherein said processing means for determining rotation and scaling parameters comprise:
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means for transforming the magnitudes of said first and second frequency domain representations into polar coordinates in the frequency domain to form first and second polar-logarithmic representations respectively;
means for transforming said first and second polar-logarithmic representations into first and second Fourier-transformed polar-logarithmic representations respectively using a two-dimensional Fast Fourier transformation;
means for extracting the phase from each of said first and second Fourier-transformed polar-logarithmic representations;
means for transforming a phase difference between said phases of said first and second Fourier-transformed polar-logarithmic representations using a two-dimensional inverse Fast Fourier transformation;
means for detecting a maximum in said phase difference;
means for determining said rotation parameter as a function of a first coordinate of said maximum; and
means for determining said scaling parameter as a function of a second coordinate of said maximum.
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25. The imaging system as recited in claim 23, wherein said processing means for determining translation parameters comprise:
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means for extracting the phase from each of said rotated and scaled first frequency domain representation and said second frequency domain representation;
means for transforming a phase difference between said phase of said rotated and scaled first frequency domain representation and said phase of said second frequency domain representation using a two-dimensional inverse Fast Fourier transformation; and
means for detecting a maximum in said phase difference, said first and second translation parameters being first and second coordinates of said maximum respectively.
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26. The imaging system as recited in claim 23, wherein said means for producing a final image frame comprise means for spatially compounding a set of image frames including at least said first image frame after said rotating, scaling and translating steps and said second image frame.
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27. The imaging system as recited in claim 23, wherein said means for producing a final image frame comprise means for reconstructing a three-dimensional image from a set of image frames including at least said first image frame after said rotating, scaling and translating steps and said second image frame.
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28. A method for image frame registration, comprising the steps of:
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storing first and second image frames of pixel values;
edge detecting said first and second image frames to form first and second edge-detected image frames respectively;
transforming said first and second edge-detected image frames into first and second frequency domain representations respectively using a two-dimensional Fast Fourier transformation;
processing said first and second frequency domain representations to determine a rotation parameter and a scaling parameter needed for said first image frame to be in registration with said second image frame;
rotating said first image frame in accordance with said rotation parameter; and
scaling said first image frame in accordance with said scaling parameter.
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29. A system for image frame registration comprising:
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a memory for storing first and second image frames of pixel values; and
an image registration processor programmed to perform the steps of;
(a) edge detecting said first and second image frames to form first and second edge-detected image frames respectively;
(b) transforming said first and second edge-detected image frames into first and second frequency domain representations respectively using a two-dimensional Fast Fourier transformation;
(c) processing said first and second frequency domain representations to determine a rotation parameter and a scaling parameter needed for said first image frame to be in registration with said second image frame;
(d) rotating said first image frame in accordance with said rotation parameter; and
(e) scaling said first image frame in accordance with said scaling parameter.
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Specification