Systems and methods for highlight recovery in an image signal processor
First Claim
1. A method for processing image data comprising:
- determining that a first pixel of the image data is clipped or near clipping;
computing a highlight recovery value for the first pixel based upon alternative pixels in the image data that are not clipped or near clipping by;
querying at least one color lookup table for color samples, the color samples comprising pre-determined reference values stored in the color lookup tables;
linearly interpolating the highlight recovery values from the color samples provided by the color lookup tables; and
applying the highlight recovery value to the first pixel by replacing the pixel value data for the clipped pixels with the highlight recovery values.
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Abstract
Image sensors have finite ranges of illuminance that may be captured. When the sensors for particular pixels receive an amount of light exceeding these finite ranges, the pixel values clip to the maximum pixel value. Systems and methods for estimating pixel values that are clipped or near clipping are provided. In one example, a method for processing image data includes determining that a first channel of the image data is saturated or near saturation. The method further includes computing a highlight recovery value for the first channel based upon alternative channels in the image data that are not saturated or near saturation. The highlight recovery value is applied to the first channel.
292 Citations
33 Claims
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1. A method for processing image data comprising:
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determining that a first pixel of the image data is clipped or near clipping; computing a highlight recovery value for the first pixel based upon alternative pixels in the image data that are not clipped or near clipping by; querying at least one color lookup table for color samples, the color samples comprising pre-determined reference values stored in the color lookup tables; linearly interpolating the highlight recovery values from the color samples provided by the color lookup tables; and applying the highlight recovery value to the first pixel by replacing the pixel value data for the clipped pixels with the highlight recovery values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An image signal processing system comprising:
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circuitry, comprising; highlight recovery logic configured to estimate and apply highlight recovery value data to image data for pixels that are clipped or near clipping, wherein clipped pixels comprise pixels having a pixel value at or above a sensor'"'"'s finite range of illuminance, wherein the highlight recovery value data is based at least in part upon pixel value data for pixels that are not clipped or near clipping; and a plurality of color lookup tables associated with color pixels of the image data; wherein the highlight recovery logic is configured to calculate and apply highlight recovery values to the clipped pixels in the image data by; querying the color lookup tables for color samples, the color samples comprising pre-determined reference values stored in the color lookup tables; linearly interpolating the highlight recovery values from the color samples provided by the color lookup tables; and replacing the pixel value data for the clipped pixels with the highlight recovery values. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. One or more non-transitory tangible computer-readable storage media having instructions encoded thereon for execution by a processor, the instructions comprising:
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code to determine a clipped pixel; code to determine a highlight recovery value to extend a pixel value of the clipped pixel beyond a saturation value of a sensor associated with the clipped pixel based at least in part upon pixel values of non-clipped pixels by; querying one or more color lookup tables for color samples, the color samples comprising pre-determined reference values stored in the color lookup tables; linearly interpolating the highlight recovery value from the color samples provided by the color lookup tables; and code to apply the highlight recovery value to the pixel value of the clipped pixel by replacing the pixel value data for the clipped pixels with the highlight recovery values. - View Dependent Claims (26, 27, 28, 29, 30)
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31. An electronic device, comprising:
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at least one digital image sensor, wherein the at least one digital image sensor has a finite range of illuminance; an interface configured to communicate with the at least one digital image sensor; a memory device; a display device configured to display a visual representation of one or more image scenes corresponding to raw image data acquired by the at least one digital image sensor; and an imaging signal processing sub-system comprising; highlight recovery logic configured to extend pixel values for clipped pixels beyond the finite range of illuminance of the at least one digital image sensor by estimating a highlight recovery value based at least in part non-clipped pixels obtained by the at least one digital image sensor by; querying one or more color lookup tables for color samples, the color samples comprising pre-determined reference values stored in the color lookup tables; linearly interpolating the highlight recovery value from the color samples provided by the color lookup tables; and applying the highlight recovery value to the pixel value of the clipped pixel by replacing the pixel value data for the clipped pixels with the highlight recovery values. - View Dependent Claims (32, 33)
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Specification