Method, apparatus and system for dynamic range estimation of imaged scenes
First Claim
Patent Images
1. An imaging device comprising:
- a pixel array;
a readout circuit for reading out digitized pixel signals from the pixel array;
a pixel processing pipeline for processing the digitized pixel signals, the processing pipeline comprising a histogram stage adapted to use un-clipped pixel data to generate automatic exposure information, andan automatic exposure circuit for adjusting image exposure parameters based on the generated automatic exposure information.
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Abstract
A method, apparatus, and system for dynamic range estimation of imaged scenes for automatic exposure control. For a given exposure time setting, certain areas of a scene may be brighter than what a camera can capture. In cameras, including those experiencing substantial lens vignetting, a gain stage may be used to extend dynamic range and extract auto-exposure data from the extended dynamic range. Alternatively, dynamic range can be extended using pre-capture image information taken under reduced exposure conditions.
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Citations
30 Claims
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1. An imaging device comprising:
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a pixel array; a readout circuit for reading out digitized pixel signals from the pixel array; a pixel processing pipeline for processing the digitized pixel signals, the processing pipeline comprising a histogram stage adapted to use un-clipped pixel data to generate automatic exposure information, and an automatic exposure circuit for adjusting image exposure parameters based on the generated automatic exposure information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A digital camera comprising:
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a lens; and an imaging device positioned to receive an image through the lens, the imaging device comprising; an image sensor, the image sensor adapted to output digitized pixel signals having a first bit-width; an image processing unit for processing un-clipped pixel data corresponding to the digital pixel signals using a histogram to obtain automatic exposure information; and an auto-exposure circuit for adjusting an exposure value for the image sensor based on the histogram automatic exposure information. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. An automatic exposure control method comprising:
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inputting pixel signals representing a scene, the signals having an N-bit width; applying a gain to the pixel signals to generate modified pixel signals having an N+M-bit width; mapping the modified pixel signals using a histogram; determining a high and a low limit of the scene dynamic range using N+M-bit information; and adjusting an exposure value for the scene based on the high and low limits. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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29. An automatic exposure method comprising:
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underexposing an image of a scene by a predetermined amount to ensure that image data does not become clipped; inputting underexposed image pixel data to an image processing pipeline; processing the underexposed image pixel data using a histogram to obtain histogram information from the image pixel data; examining the histogram to determine a high limit; and adjusting an exposure parameter based on the determined high limit. - View Dependent Claims (30)
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Specification