Adaptive Illumination for Color-Corrected Underwater Imaging
First Claim
1. An apparatus for color-corrected underwater imaging comprising:
- a plurality of optical sources each having a unique optical spectrum;
a range sensor adapted to determine a range to an underwater object to be imaged;
a memory module; and
a processor in communication with the range sensor and the memory module, the processor selecting a plurality of predetermined control values from the memory module in response to a range determined by the range sensor, the processor controlling an optical power of each of the optical sources in response to the selected predetermined control values for color-corrected imaging of the underwater object at the determined range.
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Abstract
Described are a method and an apparatus for color-corrected underwater imaging. A range to an underwater object to be imaged is determined and control values are selected according to the range. Control values are predetermined for a number of ranges according to an optimization of a color quality factor for each range based on the spectra of the optical sources used for illumination and the wavelength-dependent optical transmission of the water for the range. The optical power of each optical source is controlled according to a respective one of the selected control values. Advantageously, an acquired image requires no color correction as the adaptive illumination compensates for the wavelength-dependent losses in the light propagation path from the optical sources to the object and from the object to the imaging device.
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Citations
24 Claims
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1. An apparatus for color-corrected underwater imaging comprising:
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a plurality of optical sources each having a unique optical spectrum; a range sensor adapted to determine a range to an underwater object to be imaged; a memory module; and a processor in communication with the range sensor and the memory module, the processor selecting a plurality of predetermined control values from the memory module in response to a range determined by the range sensor, the processor controlling an optical power of each of the optical sources in response to the selected predetermined control values for color-corrected imaging of the underwater object at the determined range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for color-corrected underwater imaging, the method comprising:
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determining a range to an underwater object to be imaged; selecting a plurality of control values in response to the range, the control values being predetermined according to an optimization of a color quality factor for the range; and for each of the selected control values, controlling an optical power of an illumination of the underwater object, each illumination having a unique optical spectrum, wherein an image of the underwater object is color-corrected. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for determining a plurality of control values for controlling illumination of an underwater object using a plurality of optical sources, the method comprising:
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determining a water transmission spectrum for a plurality of ranges to the underwater object; and for each range, determining a set of control values in response to an optimization of a color quality factor for the illumination, the color quality factor being determined in response to a sum of transmission spectra, each transmission spectrum being determined as a product of an optical spectrum of a respective one of the optical sources and the water transmission spectrum for the range. - View Dependent Claims (17, 18)
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19. A method for determining a plurality of control values for controlling illumination of an underwater object using a plurality of optical sources, the method comprising:
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determining a water transmission spectrum for a plurality of ranges to the underwater object; for each range, determining an ambient light transmission spectrum for a plurality of depths, each depth being a distance between a surface of the water and the underwater object; and for each combination of one of the ranges and one of the depths, determining a set of control values in response to an optimization of a color quality factor for the illumination, the color quality factor being determined in response to a sum of transmission spectra for the range and an ambient light transmission spectrum for the depth and range, each transmission spectrum being determined as a product of an optical spectrum of a respective one of the optical sources and the water transmission spectrum for the range. - View Dependent Claims (20, 21, 22)
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23. A method for color-corrected imaging of an underwater object, the method comprising:
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selecting an RGB coefficient set from a plurality of RGB coefficient sets, each RGB coefficient set comprising an R scale factor, a G scale factor and a B scale factor for each of a red sensor, a green sensor and a blue sensor, the selection being made in response to an optical spectrum of an illumination source and a range to the underwater object; and for each pixel in a plurality of pixels in an acquired image of the underwater object, transforming an RGB value comprising an R value, a G value and a B value of the pixel to a color-corrected RGB value based on a linear combination of the respective R scale factor, the G scale factor and the B scale factor in the selected RGB coefficient set, wherein the RGB coefficient sets are predetermined for the optical spectrum of the illumination source for a plurality of ranges according to an optimization of a color quality factor. - View Dependent Claims (24)
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Specification