1. A method for enhancing a motion-blurred image, comprising:
receiving a plurality of projections, wherein the plurality of projections contain computed tomography (CT) data obtained in multiple motion phases;
generating an enhanced multi-phase image by performing an enhancement operation based on the plurality of projections; and
generating a plurality of phase-correlated images based on the plurality of projections and the enhanced multi-phase image.
2. The method as recited in claim 1, wherein the enhancement operation comprises a destreaking operation prior to forward-projecting the enhanced multi-phase image.
3. The method as recited in claim 1, wherein the generating of the enhanced multi-phase image comprising:
generating a first multi-phase image based on the plurality of projections;
generating a plurality of motion projections based on identifying moving pixels that contribute to one or more artifacts in the first multi-phase image;
generating a second multi-phase image based on the plurality of motion projections; and
generating the enhanced multi-phase image by combining the second multi-phase image with the first multi-phase image.
4. The method as recited in claim 3, wherein the generating of the plurality of motion projections comprising:
reconstructing a McKinnon-Bates (MKB) phase-correlated image based on the plurality of projections;
generating a motion map based on the MKB phase-correlated image; and
generating one of the plurality of motion projections by performing a forward-projection operation based on the motion map and the MKB phase-correlated image.
5. The method as recited in claim 1, wherein the generating of the enhanced multi-phase image comprising:
generating a first multi-phase image based on the plurality of projections; and
removing one or more streaks in the first multi-phase image with a filter.
6. The method as recited in claim 5, wherein the filter is a median filter, a bilateral filter, a neighborhood filter, or a non-local means filter with edge-preserving properties.
7. The method as recited in claim 1, wherein the generating of the enhanced multi-phase image comprising:
generating a first multi-phase image based on the plurality of projections;
segmenting the first multi-phase image into a plurality of segments;
smoothing boundaries among the plurality of segments; and
generating the enhanced multi-phase image based on the plurality of segments with smoothed boundaries.
8. The method as recited in claim 7, wherein the segmenting of the first multi-phase image comprising:
identifying a plurality of pixels from the first multi-phase image based on a intensity threshold range for a body part; and
reassigning the plurality of pixels with a mean pixel value for the body part, wherein the reassigned plurality of pixels are deemed a segment of the plurality of segments.
9. The method as recited in claim 7, wherein the smoothing of the boundaries comprising applying a filter to the plurality of segments.
10. The method as recited in claim 7, wherein the smoothing of the boundaries is not performed on stationary or near stationary segments.
11. The method as recited in claim 7, wherein the smoothing of the boundaries comprising:
replacing pixel values for a segment selected from the plurality of segments with a mean value corresponding to a body part associated with the segment;
eroding boundary regions among the plurality of segments; and
replacing the eroded boundary regions of the plurality of segments with their corresponding original pixel values.
12. A method for enhancing a motion-blurred image, comprising:
generating a first multi-phase image based on a plurality of projections, wherein the plurality of projections contain computed tomography (CT) data obtained in multiple motion phases;
generating an enhanced multi-phase image by reducing streaks in the first multi-phase image;
generating a plurality of re-projections by forward-projecting the enhanced multi-phase image;
generating a plurality of difference projections by comparing each projection selected from the plurality of projections with a corresponding re-projection selected from the plurality of re-projections;
generating a plurality of phase-correlated difference images based on the plurality of difference projections; and
generating a plurality of phase-correlated images based on the plurality of phase-correlated difference images and the enhanced multi-phase image.
13. The method as recited in claim 12, wherein the reducing of the streaks in the first multi-phase image comprising:
extracting the streaks from the first multi-phase image; and
removing the streaks from the first multi-phase image.
14. The method as recited in claim 12, wherein the reducing of the streaks in the first multi-phase image comprises applying a filter to the first multi-phase image.
15. The method as recited in claim 12, wherein the reducing of the streaks in the first multi-phase image comprising:
segmenting the first multi-phase image into a plurality of segments; and
adjusting boundary regions among the plurality of segments.
16. A machine-readable medium containing a set of instructions for enhancing a motion-blurred image which, when executed by a processor, causes the processor to:
receive a plurality of projections, wherein the plurality of projections contain computed tomography (CT) data obtained in multiple motion phases;
generate an enhanced multi-phase image by performing an enhancement operation based on the plurality of projections; and
generate a plurality of phase-correlated images based on the plurality of projections and the enhanced multi-phase image.
17. The machine-readable medium as recited in claim 16, wherein the enhancement operation comprises a destreaking operation prior to forward-projecting the enhanced multi-phase image.
18. The machine-readable medium as recited in claim 16, containing additional instructions for generating the enhanced multi-phase image, which when executed by the processor, causes the processor to:
generate a first multi-phase image based on the plurality of projections;
generate a plurality of motion projections based on identifying moving pixels that contribute to one or more artifacts in the first multi-phase image;
generate a second multi-phase image based on the plurality of motion projections; and
generate the enhanced multi-phase image by combining the second multi-phase image with the first multi-phase image.
19. The machine-readable medium as recited in claim 18, containing additional instructions for generating the plurality of motion projections, which when executed by the processor, causes the processor to:
reconstruct a McKinnon-Bates (MKB) phase-correlated image based on the plurality of projections;
generate a motion map based on the MKB phase-correlated image; and
generate one of the plurality of motion projections by performing a forward-projection operation based on the motion map and the MKB phase-correlated image.
20. The machine-readable medium as recited in claim 16, containing additional instructions for generating the enhanced multi-phase image, which when executed by the processor, causes the processor to:
generate a first multi-phase image based on the plurality of projections; and
remove one or more streaks in the first multi-phase image with a filter.
21. The machine-readable medium as recited in claim 16, containing additional instructions for generating the enhanced multi-phase image, which when executed by the processor, causes the processor to:
generate a first multi-phase image based on the plurality of projections;
segment the first multi-phase image into a plurality of segments;
smooth boundaries among the plurality of segments; and
generate the enhanced multi-phase image based on the plurality of segments with smoothed boundaries.
22. The machine-readable medium as recited in claim 21, containing additional instructions for segmenting the first multi-phase image, which when executed by the processor, causes the processor to:
identify a plurality of pixels from the first multi-phase image based on a intensity threshold range for a body part; and
reassign the plurality of pixels with a mean pixel value for the body part, wherein the reassigned plurality of pixels are deemed a segment of the plurality of segments.
23. The machine-readable medium as recited in claim 21, containing additional instructions for smoothing the boundaries, which when executed by the processor, causes the processor to:
replace pixel values for a segment selected from the plurality of segments with a mean value corresponding to a body part associated with the segment;
erode boundary regions among the plurality of segments; and
replace the eroded boundary regions of the plurality of segments with their corresponding original pixel values.
24. A machine-readable medium containing a set of instructions for enhancing a motion-blurred image which, when executed by a processor, causes the processor to:
generate a first multi-phase image based on a plurality of projections, wherein the plurality of projections contain computed tomography (CT) data obtained in multiple motion phases;
generate an enhanced multi-phase image by reducing streaks in the first multi-phase image;
generate a plurality of re-projections by forward-projecting the enhanced multi-phase image;
generate a plurality of difference projections by comparing each projection selected from the plurality of projections with a corresponding re-projection selected from the plurality of re-projections;
generate a plurality of phase-correlated difference images based on the plurality of difference projections; and
generate a plurality of phase-correlated images based on the plurality of phase-correlated difference images and the enhanced multi-phase image.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of modifying an acoustic waveform, comprising:
sampling an original waveform to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples;
analyzing each frame of samples to obtain a set of components having individual amplitudes, frequencies, and phases which, in summation, approximate the waveform of the frame, the set of components being characterized by a fundamental frequency;
modifying the individual frequencies of the set of components by a pitch-scaling factor, resulting in a set of modified components having individual pitch scaled frequencies that are characterized by a pitch-scaled fundamental frequency;
for each of the individual phases of the set of modified components, adding a phase compensation term that depends on the fundamental frequency and the pitch-scaled fundamental frequency, the phase compensation term enabling a synthesized pitch-scaled waveform to be generated having frames sizes that are substantially equal to the frame sizes of the original waveform and having phase coherence across frame boundaries.
2. The method of claim 1 further comprising:
generating the synthesized pitch-scaled waveform from the set of modified components for each frame.
3. The method of claim 1 wherein the phase compensation term is a linear term that is proportional to the pitch scaled frequencies.
4. The method of claim 3 wherein the proportion depends on a difference between a first onset time associated with the original waveform and a second onset time associated with the pitch-scaled synthesized waveform.
5. The method of claim 1 further comprises:
independently modifying a frame size of a synthesis frame containing the set of modified components by a time-scaling factor; and
the phase compensation term being further dependent on the time-scaling factor, the phase compensation term enabling a synthesized pitch-scaled and time-scaled waveform to be generated having frame sizes that differ from the frame sizes of the original waveform and having phase coherence across frame boundaries.
6. The method of claim 5 wherein phase compensation term is a linear phase term that is proportional to the pitch scaled frequencies, the proportion depending on a difference in a first onset time associated with the pitch-scaling factor and a second onset time associated with the time-scaling factor.
7. The method of claim 1 further comprising:
independently modifying the individual amplitudes and phases of the set of modified components to warp the spectral envelope of the waveform, enabling a synthesized pitch-scaled and timbre-modified waveform to be generated.
8. The method of claim 1 wherein the pitch-scaling factor is continuously variable over a defined range.
9. The method of claim 5 wherein the time-scaling factor is continuously variable over a defined range.
10. The method of claim 7 wherein warping the spectral envelope of the waveform comprises:
estimating an amplitude of the spectral envelope;
applying a linear or nonlinear mapping from the estimated spectral envelope amplitude to the warped spectral envelope; and
estimating the phase of the spectral envelope using a minimum phase assumption.
11. The method of claim 1 wherein analyzing each frame of samples to obtain a set of components having individual amplitudes, frequencies, and phases includes peak picking.
12. The method of claim 1 wherein the set of components from each frame of the original waveform or the set of modified components are coded or compressed prior to generation of the synthesized waveform.
13. The method of claim 1 wherein the set of components from each frame of the original waveform or the set of modified components are decoded or decompressed prior to generation of the synthesized waveform.
14. The method of claim 1 wherein the individual frequencies of the set of components are modified by a pitch scaling factor to compensate for quantization errors introduced by pitch quantization.
15. The method of claim 1 wherein adding a phase compensation term to the phase of each component comprises computing an onset time from an estimated fundamental frequency and phase.
16. The method of claim 1 wherein adding a phase compensation term to the phase of each component comprises computing an onset time from an estimate of a fundamental pitch period and establishing a temporal sequence of onset times therefrom.
17. The method of claim 1 wherein the set of components includes any set of sinusoidal functions with finite support in the time domain or any set of sinusoidal functions with infinite support in the time domain.
18. A method of modifying an acoustic waveform, comprising:
providing a set of components having individual amplitudes, frequencies, and phases which, in summation, approximate a frame of an acoustic waveform, the set of components being characterized by a fundamental frequency;
modifying the individual frequencies of the set of components by a pitch scaling factor, resulting in a set of modified components having individual pitch-scaled frequencies that are characterized by a pitch-scaled fundamental frequency;
for each of the individual phases of the set of modified components, adding a phase compensation term that depends on the fundamental frequency and the pitch-scaled fundamental frequency, the phase compensation term enabling a synthesized pitch-scaled waveform to be generated having frame sizes that are substantially equal to the frame sizes of the original waveform and having phase coherence across frame boundaries.
19. The method of claim 18 further comprises:
independently modifying a frame size of a synthesis frame containing the set of modified components by a time-scaling factor; and
the phase compensation term being further dependent on the time-scaling factor, the phase compensation term enabling a synthesized pitch-scaled and time-scaled waveform to be generated having frame sizes that differ from the frame sizes of the original waveform and having phase coherence across frame boundaries.
20. The method of claim 18 further comprising:
independently modifying the individual amplitudes and phases of the set of modified components to warp the spectral envelope of the waveform, enabling a synthesized pitch-scaled and timbre-modified waveform to be generated.
21. A system of modifying an acoustic waveform, comprising:
an analyzer sampling an original waveform to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples;
the analyzer analyzing each frame of samples to obtain a set of components having individual amplitudes, frequencies, and phases which, in summation, approximate the waveform of the frame, the set of components being characterized by a fundamental frequency;
a frequency-scaler modifying the individual frequencies of the set of components by a pitch-scaling factor, resulting in a set of modified components having individual pitch-scaled frequencies that are characterized by a pitch-scaled fundamental frequency;
a phase compensator, for each of the individual phases of the set of modified components, the phase compensator adding a phase compensation term that depends on the fundamental frequency and the pitch-scaled fundamental frequency, the phase compensation term enabling a synthesized pitch-scaled waveform to be generated having frames sizes that are substantially equal to the frame sizes of the original waveform and having phase coherence across frame boundaries.
22. The system of claim 21 further comprising:
a synthesizer generating the synthesized pitch-scaled waveform from the set of modified components for each frame.
23. The system of claim 21 further comprises:
a time-scaler independently modifying a frame size of a synthesis frame containing the set of modified components by a time-scaling factor; and
the phase compensation term added by the phase compensator being further dependent on the time-scaling factor, the phase compensation term enabling a synthesized pitch-scaled and time-scaled waveform to be generated having frame sizes that differ from the frame sizes of the original waveform and having phase coherence across frame boundaries.
24. The system of claim 21 further comprising:
a timbre modifier independently modifying the individual amplitudes and phases of the set of modified components to warp the spectral envelope of the waveform, enabling a synthesized pitch-scaled and timbre-modified waveform to be generated.
25. A system of modifying an acoustic waveform, comprising:
means for providing a set of components having individual amplitudes, frequencies, and phases which, in summation, approximate a frame of an acoustic waveform, the set of components being characterized by a fundamental frequency;
means for modifying the individual frequencies of the set of components by a pitch scaling factor, resulting in a set of modified components having individual pitch-scaled frequencies that are characterized by a pitch-scaled fundamental frequency;
for each of the individual phases of the set of modified components, means for adding a phase compensation term that depends on the fundamental frequency and the pitch-scaled fundamental frequency, the phase compensation term enabling a synthesized pitch-scaled waveform to be generated having frame sizes that are substantially equal to the frame sizes of the original waveform and having phase coherence across frame boundaries.
26. The system of claim 25 further comprises:
means for independently modifying a frame size of a synthesis frame containing the set of modified components by a time-scaling factor; and
the phase compensation term being further dependent on the time-scaling factor, the phase compensation term enabling a synthesized pitch-scaled and time-scaled waveform to be generated having frame sizes that differ from the frame sizes of the original waveform and having phase coherence across frame boundaries.
27. The system of claim 25 further comprising:
means for independently modifying the individual amplitudes and phases of the set of modified components to warp the spectral envelope of the waveform, enabling a synthesized pitch-scaled and timbre-modified waveform to be generated.