Global alignment for high-dynamic range image generation
First Claim
1. One or more non-transitory computer-readable media storing computer-executable instructions which when executed by a computer cause the computer to perform a method, the method comprising:
- receiving a reference image, the reference image comprising a digital image at a first exposure level and at a first time;
receiving a non-reference image, the reference image comprising a digital image at a second exposure level and at a second time, the second exposure level being different than the first exposure level, and the second time being different than the first time;
estimating two or more local motion vectors for the non-reference image relative to the reference image, the estimating of the two or more local motion vectors comprising;
downsampling the non-reference image and the reference image one or more times to form a plurality of versions of the non-reference image and the reference image at a plurality of resolutions, wherein a lowest resolution version of the non-reference image has a plurality of blocks associated as a pyramid structure to a successively larger number of blocks at corresponding locations in each higher resolution version of the non-reference image, and wherein a lowest resolution version of the reference image has a plurality of blocks associated as a pyramid structure to a successively larger number of blocks at corresponding locations in each higher resolution version of the reference image;
for the lowest resolution version of the non-reference image, estimating motion vectors of the blocks of the non-reference image by performing a search for motion vectors in the associated lowest resolution version of the reference image, wherein the search comprises searching for matching blocks at nearby block locations then expanding the search; and
for each successively higher resolution version of the non-reference image, estimating motion vectors of the blocks of the successively higher resolution version of the non-reference image using a refinement search starting from the motion vector estimated for the associated block of the preceding lower resolution version of the non-reference image according to the pyramid structure.
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Accused Products
Abstract
Techniques and tools for high dynamic range (“HDR”) image generation and rendering are described herein. In several described embodiments, images having distinct exposure levels are aligned. In particular embodiments, the alignment of a reference image to a non-reference image is based at least in part on motion vectors that are determined using covariance computations. Furthermore, in certain embodiments, saturated areas, underexposed areas, and/or moving objects are ignored or substantially ignored during the image alignment process. Moreover, in certain embodiments, a hierarchical pyramid block-based scheme is used to perform local motion estimation between the reference image and the non-reference image.
54 Citations
18 Claims
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1. One or more non-transitory computer-readable media storing computer-executable instructions which when executed by a computer cause the computer to perform a method, the method comprising:
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receiving a reference image, the reference image comprising a digital image at a first exposure level and at a first time; receiving a non-reference image, the reference image comprising a digital image at a second exposure level and at a second time, the second exposure level being different than the first exposure level, and the second time being different than the first time; estimating two or more local motion vectors for the non-reference image relative to the reference image, the estimating of the two or more local motion vectors comprising; downsampling the non-reference image and the reference image one or more times to form a plurality of versions of the non-reference image and the reference image at a plurality of resolutions, wherein a lowest resolution version of the non-reference image has a plurality of blocks associated as a pyramid structure to a successively larger number of blocks at corresponding locations in each higher resolution version of the non-reference image, and wherein a lowest resolution version of the reference image has a plurality of blocks associated as a pyramid structure to a successively larger number of blocks at corresponding locations in each higher resolution version of the reference image; for the lowest resolution version of the non-reference image, estimating motion vectors of the blocks of the non-reference image by performing a search for motion vectors in the associated lowest resolution version of the reference image, wherein the search comprises searching for matching blocks at nearby block locations then expanding the search; and for each successively higher resolution version of the non-reference image, estimating motion vectors of the blocks of the successively higher resolution version of the non-reference image using a refinement search starting from the motion vector estimated for the associated block of the preceding lower resolution version of the non-reference image according to the pyramid structure. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A digital image processing device for generating HDR images, the digital image processing device comprising:
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a memory storing an image alignment program; at least one digital signal processing component; a processing unit operable to execute the image alignment program, wherein said execution of the image alignment program causes the processing unit to; input a reference image, the reference image comprising a digital image at a first exposure level and at a first time; input a non-reference image, the reference image comprising a digital image at a second exposure level and at a second time, the second exposure level being different than the first exposure level, and the second time being different than the first time; and compute a local motion vector for a block of pixel sample values in the non-reference image indicating relative motion of the block to a corresponding block of pixel sample values in the reference image, the local motion vector being determined at least in part using a metric measuring how the pixel sample values in the block in the non-reference image change together with the pixel sample values in the block in the reference image. - View Dependent Claims (9)
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10. A method, the method comprising:
by computing hardware; receiving a reference image, the reference image comprising a digital image at a first exposure level and at a first time; receiving a non-reference image, the reference image comprising a digital image at a second exposure level and at a second time, the second exposure level being different than the first exposure level, and the second time being different than the first time; estimating two or more local motion vectors for the non-reference image relative to the reference image, the estimating of the two or more local motion vectors comprising; downsampling the non-reference image and the reference image one or more times to form a plurality of versions of the non-reference image and the reference image at a plurality of resolutions, wherein a lowest resolution version of the non-reference image has a plurality of blocks associated as a pyramid structure to a successively larger number of blocks at corresponding locations in each higher resolution version of the non-reference image, and wherein a lowest resolution version of the reference image has a plurality of blocks associated as a pyramid structure to a successively larger number of blocks at corresponding locations in each higher resolution version of the reference image; for the lowest resolution version of the non-reference image, estimating motion vectors of the blocks of the non-reference image by performing a search for motion vectors in the associated lowest resolution version of the reference image, wherein the search comprises searching for matching blocks at nearby block locations then expanding the search; and for each successively higher resolution version of the non-reference image, estimating motion vectors of the blocks of the successively higher resolution version of the non-reference image using a refinement search starting from the motion vector estimated for the associated block of the preceding lower resolution version of the non-reference image according to the pyramid structure. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A digital image processing method for generating HDR images, the method comprising:
by computing hardware; inputting a reference image, the reference image comprising a digital image at a first exposure level and at a first time; inputting a non-reference image, the reference image comprising a digital image at a second exposure level and at a second time, the second exposure level being different than the first exposure level, and the second time being different than the first time; and computing a local motion vector for a block of pixel sample values in the non-reference image indicating relative motion of the block to a corresponding block of pixel sample values in the reference image, the local motion vector being determined at least in part using a metric measuring how the pixel sample values in the block in the non-reference image change together with the pixel sample values in the block in the reference image. - View Dependent Claims (18)
Specification