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US 6,748,115 B1Granted
Perceptually lossless image compression
AssigneeCVISION Technologies, Inc.
InventorAri Gross
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AssigneeCVISION Technologies, Inc.
InventorAri Gross
Estimating the term…
An image compression technique employs selecting a gray level threshold value for converting a gray level digital image input into a bi-level input which minimizes weak connectivity, wherein weak connectivity comprises a checkerboard pattern found in a 2×2 array or neighborhood of pixels. The threshold value is determined by traversing the array of pixels comprising the document in a single path, examining successive 2×2 neighborhoods and incrementing a plus register for the gray level value which a checkerboard pattern first appears and incrementing a minus register for the gray level value at which the checkerboard pattern no longer exists. The total number of weak connectivity checkerboards for each gray level threshold value is calculated based upon the difference between the values stored in the registers. An improved distance measure for determining a match between models comprises a modification of the Hausdorff measure by limiting such measure to a single quadrant, resulting in a lower mismatch rate.
In a method for perceptually lossless image compression, the improvement comprising the step of converting gray level pixel image data to bi-level image data as a function of weak connectivity, the step of converting including determining the gray level threshold value resulting in minimal weak connectivity and utilizing such threshold value for conversion to a bi-level image.
In a method for perceptually lossless image compression, the improvement comprising the step of converting gray level pixel image data to bi-level image data as a function of weak connectivity, the improvement further comprising selecting a gray level threshold value which results in the lowest weak connectivity.
In a method for perceptually lossless image compression, the improvement comprising the step of converting gray level pixel image data to bi-level image data as a function of weak connectivity, the improvement further comprising examining successive 2×2 matrices of pixels, incrementing a plus register for the gray level value at which a checkerboard pattern first appears and incrementing a minus register for the gray level value at which a checkerboard pattern no longer exists.
A method for determining symbol matching in a perceptually lossless image compression system, the method comprising accepting as a match, symbols wherein the deviations are limited to a directional Hausdorff distance from the periphery of the symbols.
A method of converting gray level pixel image data to a bi-level image, the method comprising the following steps:
A method of generating a weak connectivity histogram of gray level pixel image data, the method comprising the steps of:
A method of processing pixel image data for perceptually lossless image compression, the method including the steps of:
Dependencies are inferred from the claim text.