Abstract:
A system and method for searching an incident light field for atypical regions (e.g., hot spots or cool spots or spectrally distinctive regions) within the incident light field using a light modulator and a spectral sensing device. Once the atypical regions are identified, the light modulator may be used to mask the incident light field so that the spectral sensing device can make spatially-concentrated measurements of the wavelength spectrum of the atypical regions (or alternatively, the exterior of the atypical regions). Furthermore, in a compressive imaging mode, a sequence of spatial patterns may be supplied to the light modulator, and a corresponding sequence of wavelength spectra may be collected from the spectral sensing device. The wavelength spectra comprise a compressed representation of the incident light field over space and wavelength. The wavelength spectra may be used to reconstruct a multispectral (or hyperspectral) data cube.
Abstract:
An imaging system and method that captures compressive sensing (CS) measurements of a received light stream, and also obtains samples of background light level (BGLL). The BGLL samples may be used to compensate the CS measurements for variations in the BGLL. The system includes: a light modulator to spatially modulate the received light stream with spatial patterns, and a lens to concentrate the modulated light stream onto a light detector. The samples of BGLL may be obtained in various ways: (a) injecting calibration patterns among the spatial patterns; (b) measuring complementary light reflected by digital micromirrors onto a secondary output path; (c) separating and measuring a portion of light from the optical input path; (d) low-pass filtering the CS measurements; and (e) employing a light power meter with its own separate input path. Also, the CS measurements may be high-pass filtered to attenuate background light variation.
Abstract:
If a Hadamard matrix HN of order N=BF is a Kronecker product HFHB of an order F Hadamard matrix and an order B Hadamard matrix, then transformation by HN may be implemented by a fast Hadamard transform at coarse scale followed by fast Hadamard transforms at fine scale. Alternatively, transformation by HN may be achieved by performing order B transforms on columns of a two-dimensional array and order B transforms on rows of the array. As another alternative, transformation by HN may be achieved by computing intermediate values based on linear combinations of input elements and then computing linear combinations of the intermediate values. For compressive signal acquisition, any row of HN may be generated by concatenating selectively modified copies of a corresponding row of HB. Thus, modulation patterns may be generated on the fly.
Abstract:
A mechanism for reconstructing sub-images based on measurement data acquired by an imaging system including an array of light modulating elements and an array of photodetectors. Each sub-image is reconstructed based on samples from a respective photodetector and a respective set of measurement patterns defined on a respective virtual sub-region on the modulating array. Each virtual sub-region is configured to include at least the light modulating elements that are able to send a non-trivial amount of light to the respective photodetector during a pattern application period. The virtual sub-regions overlap because many light modulating elements are capable of sending light to more than one photodetector. Whenever a measurement pattern of one virtual sub-region overlaps the measurement pattern of a neighboring virtual sub-region, the two measurement patterns agree by design. Thus, the measurement patterns for the collection of virtual sub-regions combine to form a pattern on the whole modulating array.
Abstract:
An imaging system and method that captures compressive sensing (CS) measurements of a received light stream, and also obtains samples of background light level (BGLL). The BGLL samples may be used to compensate the CS measurements for variations in the BGLL. The system includes: a light modulator to spatially modulate the received light stream with spatial patterns, and a lens to concentrate the modulated light stream onto a light detector. The samples of BGLL may be obtained in various ways: (a) injecting calibration patterns among the spatial patterns; (b) measuring complementary light reflected by digital micromirrors onto a secondary output path; (c) separating and measuring a portion of light from the optical input path; (d) low-pass filtering the CS measurements; and (e) employing a light power meter with its own separate input path. Also, the CS measurements may be high-pass filtered to attenuate background light variation.
Abstract:
If a Hadamard matrix HN of order N=BF is a Kronecker product HF HB of an order F Hadamard matrix and an order B Hadamard matrix, then transformation by HN may be implemented by a fast Hadamard transform at coarse scale followed by fast Hadamard transforms at fine scale. Alternatively, transformation by HN may be achieved by performing order B transforms on columns of a two-dimensional array and order B transforms on rows of the array. As another alternative, transformation by HN may be achieved by computing intermediate values based on linear combinations of input elements and then computing linear combinations of the intermediate values. For compressive signal acquisition, any row of HN may be generated by concatenating selectively modified copies of a corresponding row of HB. Thus, modulation patterns may be generated on the fly.
Abstract:
A mechanism for reconstructing sub-images based on measurement data acquired by an imaging system including an array of light modulating elements and an array of photodetectors. Each sub-image is reconstructed based on samples from a respective photodetector and a respective set of measurement patterns defined on a respective virtual sub-region on the modulating array. Each virtual sub-region is configured to include at least the light modulating elements that are able to send a non-trivial amount of light to the respective photodetector during a pattern application period. The virtual sub-regions overlap because many light modulating elements are capable of sending light to more than one photodetector. Whenever a measurement pattern of one virtual sub-region overlaps the measurement pattern of a neighboring virtual sub-region, the two measurement patterns agree by design. Thus, the measurement patterns for the collection of virtual sub-regions combine to form a pattern on the whole modulating array.
Abstract:
A system and method for searching an incident light field for atypical regions (e.g., hot spots or cool spots or spectrally distinctive regions) within the incident light field using a light modulator and a spectral sensing device. Once the atypical regions are identified, the light modulator may be used to mask the incident light field so that the spectral sensing device can make spatially-concentrated measurements of the wavelength spectrum of the atypical regions (or alternatively, the exterior of the atypical regions). Furthermore, in a compressive imaging mode, a sequence of spatial patterns may be supplied to the light modulator, and a corresponding sequence of wavelength spectra may be collected from the spectral sensing device. The wavelength spectra comprise a compressed representation of the incident light field over space and wavelength. The wavelength spectra may be used to reconstruct a multispectral (or hyperspectral) data cube.