Data compression/decompression device and data compression/decompression method
AssigneesCasio Electronics Manufacturing Co., Ltd., Casio Computer Co., Ltd.
InventorMiyoshi Sasakura
Life of this patent
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Abstract
A first compression unit compresses input data by a first compression method utilizing a dictionary coding method. A second decompression unit compresses input data by a second compression method utilizing a statistical coding method. A size calculation/determination unit pre-calculates sizes of data to be output when the data is compressed only by the first compression method, when the data is compressed only by the second compression method, when the data is compressed both by the first and second compression methods, and when the data is compressed neither by the first nor the second compression method, and selects the method that will result in the smallest data size, so that the input data is compressed by the selected method.
Claims20
A data compression device, comprising:
- a first data compression unit which performs a first data compression process for compressing input data by a dictionary coding method;
- and
- a second data compression unit which performs a second data compression process for compressing the data compressed by the first data compression unit by a statistical coding method,
- wherein the first data compression unit searches for longest data that corresponds to the input data from already coded data in a dictionary, and decompresses the input data in a byte unit.
A data decompression device, comprising:
- a first decompression unit which decompresses compressed data by a method corresponding to a statistical coding method;
- and
- a second decompression unit which further decompresses the data decompressed by the first decompression unit by a method corresponding to a dictionary coding method.
A data compression method, comprising:
- a first data compressing step of performing a first data compression process for compressing input data by a dictionary coding method;
- and
- a second data compressing step of performing a second data compression process for compressing the data compressed at the first data compressing step by a statistical coding method,
- wherein at the first data compressing step, longest data that corresponds to the input data is searched out from already coded data in a dictionary, compressed, and output in a byte unit.
A data decompression method, comprising:
- a first data decompressing step of decompressing compressed data by a method corresponding to a statistical coding method;
- and
- a second data decompressing step of further decompressing the data decompressed at the first data decompressing step by a method corresponding to a dictionary coding method.
Dependencies are inferred from the claim text.