Apparatus and methods for recompression of digital images
First Claim
Patent Images
1. A computerized method of iteratively searching for a target value of a compression parameter to be used in optimized image compression of an input image, the method comprising:
- selecting an initial value of the compression parameter at least based on one or more characteristics of the input image;
compressing the input image using the initial value, giving rise to a candidate compressed image;
determining whether quality of the candidate compressed image meets a perceptual quality criterion; and
in response to the perceptual quality criterion being not met, iteratively searching for a target value of the compression parameter by;
iteratively, generating an updated value of the compression parameter and repeating said compressing and determining using the updated value, until the perceptual quality criterion is met by an updated compressed image, and selecting the updated value used to obtain the updated compressed image to be the target value of the compression parameter.
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Abstract
A system and method for generating a second reduced size digital image from a first digital image, the method including iteratively compressing the first digital image to an extent determined by a quality measure comprising at least a blockiness measure quantifying added artifactual edges along coding block bomldaries of the second image and/or use of a quantization matrix generated by computing a weighted average of the quantization matrix of the first digital image and a scaled second quantization matrix.
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Citations
22 Claims
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1. A computerized method of iteratively searching for a target value of a compression parameter to be used in optimized image compression of an input image, the method comprising:
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selecting an initial value of the compression parameter at least based on one or more characteristics of the input image; compressing the input image using the initial value, giving rise to a candidate compressed image; determining whether quality of the candidate compressed image meets a perceptual quality criterion; and in response to the perceptual quality criterion being not met, iteratively searching for a target value of the compression parameter by;
iteratively, generating an updated value of the compression parameter and repeating said compressing and determining using the updated value, until the perceptual quality criterion is met by an updated compressed image, and selecting the updated value used to obtain the updated compressed image to be the target value of the compression parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A computerized system of iteratively searching for a target compression parameter to be used in optimized image compression of an input image, the system comprising a processor operatively coupled to a memory, the processor configured to:
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select an initial value of the compression parameter at least based on one or more characteristics of the input image; compress the input image using the initial value, giving rise to a candidate compressed image; determine whether quality of the candidate compressed image meets a perceptual quality criterion; and in response to the perceptual quality criterion being not met, iteratively search for a target value of the compression parameter by;
iteratively, generating an updated value of the compression parameter and repeating said compressing and determining using the updated value, until the perceptual quality criterion is met by an updated compressed image, and selecting the updated value used to obtain the updated compressed image to be the target value of the compression parameter. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A non-transitory computer readable storage medium tangibly embodying a program of instructions executable by a computer to perform a method of iteratively searching for a target value of a compression parameter to be used in optimized image compression of an input image, the method comprising:
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selecting an initial value of the compression parameter at least based on one or more characteristics of the input image; compressing the input image using the initial value, giving rise to a candidate compressed image; determining whether quality of the candidate compressed image meets a perceptual quality criterion; and in response to the perceptual quality criterion being not met, iteratively searching for a target value of the compression parameter by;
iteratively, generating an updated value of the compression parameter and repeating said compressing and determining using the updated value, until the perceptual quality criterion is met by an updated compressed image, and selecting the updated value used to obtain the updated compressed image to be the target value of the compression parameter.
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Specification