Methods, systems and apparatuses for high-quality green imbalance compensation in images
First Claim
Patent Images
1. A method of processing a plurality of pixel signals corresponding to an image comprising:
- determining an estimated green balance correction term for each green pixel signal;
determining a limited green balance correction term for each green pixel signal by limiting the estimated green balance correction term based on a set of parameters; and
adjusting each green pixel signal by applying the limited green balance correction term to the green pixel signal.
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Accused Products
Abstract
Methods, systems and apparatuses for determining and compensating for green imbalance in imagers. An estimated local green balance correction term is limited, e.g., between an upper and lower limit. The upper and lower limits are determined from a set of parameters. The parameters are determined during a calibration procedure. The parameters may be stored for a subset of possible pixel locations and parameters for each pixel not at a location corresponding to stored data may be determined by interpolation.
17 Citations
25 Claims
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1. A method of processing a plurality of pixel signals corresponding to an image comprising:
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determining an estimated green balance correction term for each green pixel signal; determining a limited green balance correction term for each green pixel signal by limiting the estimated green balance correction term based on a set of parameters; and adjusting each green pixel signal by applying the limited green balance correction term to the green pixel signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of operating an imaging system, the method comprising:
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acquiring a plurality of test images; developing parameters for limiting green imbalance color correction terms from the test images; and storing the parameters in an imager for use in correction of green color imbalance by the imager. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. An imaging device comprising:
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an array of pixels for capturing an image and providing pixel signals; a storage device for storing at least one set of parameters; and a processing circuit for processing pixel output signals produced by the array and corresponding to a captured image, the processing circuit being configured to; determine an estimated green balance correction term for each green pixel output signal; determine a limited green balance correction term for each green pixel output signal by limiting the estimated green balance correction term by applying at least one of an upper limit and a lower limit to the estimated green balance correction term, wherein the upper and lower limits are determined from the at least one set of parameters; and adjust each green pixel output signal by applying the limited green balance correction term to the green pixel signal. - View Dependent Claims (19, 20, 21, 22)
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23. A digital camera comprising:
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a pixel array for capturing an image received through a lens; a storage area for storing at, least one set of parameters; and a pixel array processing circuit which, using the at least one set of parameters, is configured to determine a limited green balance correction term, and to adjust green pixel signals for a captured image using the limited green balance correction term, wherein the limited green balance correction term is determined by limiting an estimated green balance correction term using the at least one set of parameters, and wherein the estimated green balance correction term is limited such that the limited green balance correction term is greater than or equal to a lower limit and less than or equal to an upper limit, wherein the lower and upper limits are determined from the at least one set of parameters. - View Dependent Claims (24)
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25. A non-transitory computer readable medium having stored thereon a computer program comprising a set of instructions executed by a computer to implement a method for green imbalance correction, the method comprising the acts of:
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determining an estimated green balance correction term for each green pixel signal associated with a captured image, wherein determining the estimated green balance correction term comprises; determining a first average of pixel signals in a pixel kernel surrounding a particular green pixel being processed and belong to a first green color channel, wherein the particular pixel belongs to the first green color channel; determining a second average of pixel signals in a pixel kernel surrounding the particular green pixel and belong to a second green color channel; and determining the estimated green balance correction term based on a difference between the first average and the second average; determining a limited green balance correction term for each green pixel signal by limiting the estimated green balance correction term by applying at least one of an upper limit and a lower limit to the estimated green balance correction term, wherein the upper and lower limits are determined from a set of parameters, the set of parameters being related to at least one of an array location of a particular green pixel signal, a sensor which captures the image and camera optics of a camera which captures the image, and the set of parameters being obtained by; obtaining from a storage location, for each parameter, a set of available values associated with an array location nearest the particular green pixel being adjusted; and using interpolation to determine the set of parameters for the green particular pixel being adjusted; and adjusting each green pixel signal by applying the limited green balance correction term to the green pixel signal.
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Specification