Image adjustment based on locally flat scenes
First Claim
1. A method for adjusting an image using one or more images of locally flat scenes acquired with an imaging system comprising an imaging sensor with an array of photodetectors, the method comprising:
- acquiring image data with the array of photodetectors, the image data comprising an array of pixel intensity values;
dividing at least a portion of the image data into a plurality of kernels;
determining local contrast values for individual kernels, a local contrast value of an individual kernel based at least in part on pixel values within the individual kernel;
determining that the image frame is a locally flat image if the local contrast values for at least a predetermined number of the individual kernels are less than or equal to a contrast threshold; and
in response to determining that the image frame is a locally flat image;
calculating an array of pixel adjustment values to generate an offset mask configured to adjust the pixel intensity values of the image data; and
adjusting pixel intensity values of subsequently acquired image data using the offset mask.
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Abstract
Imaging systems and methods are disclosed that use locally flat scenes to adjust image data. An imaging system includes an array of photodetectors configured to produce an array of intensity values corresponding to light intensity at the photodetectors. The imaging system can be configured to acquire a frame of intensity values, or an image frame, and analyze the image frame to determine if it is locally flat. If the image frame is locally flat, then that image data can be used to determine gradients present in the image frame. An offset mask can be determined from the image data and that offset mask can be used to adjust subsequently acquired image frames to reduce or remove gradients.
77 Citations
20 Claims
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1. A method for adjusting an image using one or more images of locally flat scenes acquired with an imaging system comprising an imaging sensor with an array of photodetectors, the method comprising:
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acquiring image data with the array of photodetectors, the image data comprising an array of pixel intensity values; dividing at least a portion of the image data into a plurality of kernels; determining local contrast values for individual kernels, a local contrast value of an individual kernel based at least in part on pixel values within the individual kernel; determining that the image frame is a locally flat image if the local contrast values for at least a predetermined number of the individual kernels are less than or equal to a contrast threshold; and in response to determining that the image frame is a locally flat image; calculating an array of pixel adjustment values to generate an offset mask configured to adjust the pixel intensity values of the image data; and adjusting pixel intensity values of subsequently acquired image data using the offset mask. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A thermal imaging system comprising:
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an imaging array comprising an infrared focal plane array, the infrared focal plane array configured to generate signals corresponding to levels of infrared light incident on the infrared focal plane array; a detector circuit comprising readout electronics that receive the generated signals and output image data comprising an array of pixel intensity values; and a system controller configured to; divide at least a portion of the image data into a plurality of kernels; determine local contrast values for individual kernels, a local contrast value of an individual kernel based at least in part on pixel intensity values within the individual kernel; determine that the image frame is a locally flat image if the local contrast values for at least a predetermined number of the individual kernels are less than or equal to a contrast threshold; and in response to determining that the image frame is a locally flat image; calculate an array of pixel adjustment values to generate an offset mask; and adjust pixel intensity values of subsequently acquired image data using the offset mask. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification