Systems and methods of suppressing sky regions in images
First Claim
1. A system comprising:
- a memory configured to store an image of a scene including a sky region and a ground region; and
a processor configured to communicate with the memory, the processor configured to;
detect an approximate location of a horizon in the image based on one or more of;
a tilt measurement from an orientation sensor, an edge detection information from processing the image, or pixel coordinates provided by a user;
identify the sky region in the image based on the detected location of the horizon;
assign pixels corresponding to the sky region as sky region pixels and assign remaining pixels as ground region pixels;
receive pixel values indicative of irradiance levels from each of the assigned sky region pixels;
count the number of occurrences of each pixel value of the received pixel values;
select one or more ranges of pixel values having the number of occurrences greater than a predetermined threshold number based on the counted number of occurrences to determine one or more dynamic ranges attributable to the sky region;
generate a transfer function to apply to the entire image including the sky region and the ground region, the generated transfer function being configured to compress the one or more dynamic ranges attributable to the sky region and to expand a dynamic range attributable to the ground region; and
apply the transfer function to the image.
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Abstract
Various techniques are provided for systems and methods to process images to reduce consumption of an available output dynamic range by the sky in images. For example, according to one or more embodiments of the disclosure, a region or area in images that may correspond to the sky may be identified based on the location of the horizon in the images. A distribution of irradiance levels in the identified sky region may be analyzed to determine a dynamic range attributable to the sky region. A transfer function that compresses the dynamic range attributable to the sky region may be generated and applied so that the sky in the images may be suppressed, thereby advantageously preserving more dynamic range for terrestrial objects and other objects of interest in the images.
186 Citations
18 Claims
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1. A system comprising:
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a memory configured to store an image of a scene including a sky region and a ground region; and a processor configured to communicate with the memory, the processor configured to; detect an approximate location of a horizon in the image based on one or more of;
a tilt measurement from an orientation sensor, an edge detection information from processing the image, or pixel coordinates provided by a user;identify the sky region in the image based on the detected location of the horizon; assign pixels corresponding to the sky region as sky region pixels and assign remaining pixels as ground region pixels; receive pixel values indicative of irradiance levels from each of the assigned sky region pixels; count the number of occurrences of each pixel value of the received pixel values; select one or more ranges of pixel values having the number of occurrences greater than a predetermined threshold number based on the counted number of occurrences to determine one or more dynamic ranges attributable to the sky region; generate a transfer function to apply to the entire image including the sky region and the ground region, the generated transfer function being configured to compress the one or more dynamic ranges attributable to the sky region and to expand a dynamic range attributable to the ground region; and apply the transfer function to the image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 17)
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9. A method comprising:
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receiving an image of a scene including a sky region and a ground region; detecting an approximate location of a horizon in the image based on one or more of;
a tilt measurement from an orientation sensor, an edge detection information from processing the image, or pixel coordinates provided by a user;identifying the sky region in the image based on the detected location of the horizon; assigning pixels corresponding to the sky region as sky region pixels and assigning remaining pixels as ground region pixels; counting the number of occurrences of each pixel value of the received pixel values; selecting one or more ranges of pixel values having the number of occurrences greater than a predetermined threshold number based on the counted number of occurrences to determine one or more dynamic ranges attributable to the sky region; generating a transfer function to apply to the entire image including the sky region and the ground region, the generated transfer function compressing the one or more dynamic ranges attributable to the sky region and to expand a dynamic range attributable to the ground region; and applying the transfer function to the image. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 18)
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Specification