Quantization method for image data compression employing context modeling algorithm
First Claim
1. A method for performing data compression on data elements of a body of input data, each data element having a respective context, the method comprising the steps of:
- quantizing each of the data elements separately, based on the context of that data element, thereby performing a lossy data compression of the data elements;
dividing the quantized data elements, by value, into a predetermined number of categories;
for each of the categories, selecting a respective value as a single quantized value to represent each of the data elements of the category;
determining whether the body of input data to be compressed has a dependency; and
,responsive to a determination by the step of determining that the body of input data has a dependency, constructing a model to account for the dependency.
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Abstract
A method, system, and manufacture are provided, for use in connection with data processing and compression, for quantizing a string of data values, such as image data pixel values. The quantization is achieved by grouping the data values, based on their values, into a predetermined number of categories, each category containing the same total number of values. For each category, a value, preferably a mean value of those in the category, is selected as a quantization value. All of the data values in the category arc then represented by the selected quantization value. For data strings having a dependency (that is, the values of one or more of the data values provide information about values of other of the data values), the dependency is modeled by a method in which a modeling algorithm defines contexts in terms of a tree structure, and the basic method of grouping into categories and selecting a quantization value for each category is performed on a per node (i.e., per context) basis.
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Citations
18 Claims
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1. A method for performing data compression on data elements of a body of input data, each data element having a respective context, the method comprising the steps of:
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quantizing each of the data elements separately, based on the context of that data element, thereby performing a lossy data compression of the data elements; dividing the quantized data elements, by value, into a predetermined number of categories; for each of the categories, selecting a respective value as a single quantized value to represent each of the data elements of the category; determining whether the body of input data to be compressed has a dependency; and
,responsive to a determination by the step of determining that the body of input data has a dependency, constructing a model to account for the dependency. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system for performing data compression on data elements of a body of input data, each data element having a respective context, the system comprising:
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means for quantizing each of the data elements separately, based on the context of that data element, thereby performing a lossy data compression of the data elements; means for dividing the quantized data elements, by value, into a predetermined number of categories; means, operable for each of the categories, for selecting a respective value as a single quantized value to represent each of the data elements of the category; means for determining whether the body of input data to be compressed has a dependency; and means operable responsive to a determination by the step of determining that the body of input date has a dependency, for constructing a model to account for the dependency. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A computer program product, for use with a data processing system, for performing data compression on data elements of a body of input data, each data element having a respective context, the computer program product comprising:
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a computer-usable medium; means, provided on the computer-usable medium, for directing the data processing system to quantize each of the data elements separately, based on the context of that data element, thereby performing a lossy data compression of the data elements; means, provided on the computer-usable medium, for directing the data processing system to divide the quantized data elements, by value, into a predetermined number of categories; means, provided on the computer-usable medium, operable for each of the categories, for directing the data processing system to select a respective value as a single quantized value to represent each of the data elements of the category; means, provided on the computer-usable medium for directing the data processing system to determine whether the body of input data to be compressed has a dependency; and
,means operable responsive to a determination by the step of determining that the body of input date has a dependency, provided on the computer-usable medium for directing the data processing system to construct a model to account for the dependency. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification