Method for image processing using local statistics convolution
AssigneeGoogle Inc.
InventorNils Kokemohr
Life of this patent
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Abstract
A method for filtering a digital image, comprising segmenting the digital image into a plurality of tiles; computing tile histograms corresponding to each of the plurality of tiles; deriving a plurality of tile transfer functions from the tile histograms preferably using 1D convolutions; interpolating a tile transfer function from the plurality of tile transfer functions; and filtering the digital image with the interpolated tile transfer function. Many filters otherwise difficult to conceive or to implement are possible with this method, including an edge-preserving smoothing filter, HDR tone mapping, edge invariant gradient or entropy detection, image upsampling, and mapping coarse data to fine data.
Claims20
A method for filtering a digital image, the method comprising:
- calculating a regional histogram corresponding to one or more regions in a first plurality of regions, each of the first plurality of regions comprising a plurality of pixels of the digital image;
- calculating for each region in the first plurality of regions a regional transfer function comprising a convolution of the corresponding regional histogram with a first convolution kernel;
- and
- filtering the digital image with an image transfer function based on at least one of the regional transfer functions.
A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps to transform a digital image, said method steps comprising:
- calculating a regional histogram corresponding to each region in the first plurality of regions, each of the first plurality of regions comprising a plurality of pixels in the digital image;
- calculating for each region in the first plurality of regions a regional transfer function comprising a convolution of the corresponding regional histogram with a first convolution kernel;
- and
- filtering the digital image by applying the with an image transfer function based on at least one of the regional transfer functions to each of the first plurality of pixels.
A system comprising:
- one or more processors coupled to a program storage device readable by the one or more processors, tangibly embodying a program of instructions executable by the one or more processors to perform operations to transform a digital image, said operations including:
- calculating a regional histogram corresponding to each region in the first plurality of regions, each of the first plurality of regions comprising a plurality of pixels in the digital image;
- calculating for each region in the first plurality of regions a regional transfer function comprising a convolution of the corresponding regional histogram with a first convolution kernel;
- and
- filtering the digital image by applying the with an image transfer function based on at least one of the regional transfer functions to each of the first plurality of pixels.
Dependencies are inferred from the claim text.