Image encoding apparatus and image decoding apparatus
First Claim
1. An image encoding apparatus comprising:
- input means for inputting image data;
discrimination means for discriminating if each of a plurality of regions, which form the image data input by said input means, is a region of a first type, a quality of which becomes not more than a predetermined quality if the region is compressed at a predetermined compression ratio, or is a region of a second type, a quality of which exceeds the predetermined quality if the region is compressed at the predetermined compression ratio;
selection means for selecting an encoding method used in compression of the region on the basis of the type of each region discriminated by said discrimination means;
first compression means for compressing the region by the encoding method selected by said selection means; and
second compression means for compressing information associated with the type of region.
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Abstract
This invention has as its object to efficiently compress a mixed image which includes both natural and non-natural images upon encoding and decoding image data.
To achieve this object, in an image encoding apparatus according to this invention, a line buffer (101) segments image data (131) input from an image scanner (130) for inputting image data into a plurality of regions, a discrimination unit (120) discriminates the ratio of regions each having a predetermined nature to the image data (131), a quantization matrix selector (121) selects a quantization matrix used to compress the region on the basis of this ratio, an image data encoder (103) compresses the region using the selected quantization matrix, and an attribute flag encoder (102) compresses information which helps the decoding side estimate a quantization matrix used to encode the region.
79 Citations
108 Claims
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1. An image encoding apparatus comprising:
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input means for inputting image data;
discrimination means for discriminating if each of a plurality of regions, which form the image data input by said input means, is a region of a first type, a quality of which becomes not more than a predetermined quality if the region is compressed at a predetermined compression ratio, or is a region of a second type, a quality of which exceeds the predetermined quality if the region is compressed at the predetermined compression ratio;
selection means for selecting an encoding method used in compression of the region on the basis of the type of each region discriminated by said discrimination means;
first compression means for compressing the region by the encoding method selected by said selection means; and
second compression means for compressing information associated with the type of region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 75, 76, 77, 78, 79, 87)
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21. An image decoding apparatus for decoding encoded data, which is obtained by encoding a plurality of regions that form image data as units, to obtain the image data, comprising:
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storage means for storing the encoded data;
first decoding means for decoding the encoded data stored in said storage means to obtain information associated with a type of region to be decoded;
discrimination means for discriminating, based on the information associated with the type of region decoded by said first decoding means, if the region is a region of a first type, a quality of which becomes not more than a predetermined quality if the region is compressed at a predetermined compression ratio, or is a region of a second type, a quality of which exceeds the predetermined quality if the region is compressed at the predetermined compression ratio;
selection means for selecting a decoding method used to decode the region on the basis of the information associated with the type of each region discriminated by said discrimination means; and
second decoding means for decoding the region by the decoding method selected by said selection means. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 88)
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37. An image encoding method comprising:
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the input step of inputting image data;
the discrimination step of discriminating if each of a plurality of regions, which form the image data input in the input step, is a region of a first type, a quality of which becomes not more than a predetermined quality if the region is compressed at a predetermined compression ratio, or is a region of a second type, a quality of which exceeds the predetermined quality if the region is compressed at the predetermined compression ratio;
the selection step of selecting an encoding method used in compression of the region on the basis of the type of each region discriminated in the discrimination step;
the first compression step of compressing the region by the encoding method selected in the selection step; and
the second compression step of compression information associated with the type of region. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 73)
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57. An image decoding method for decoding encoded data, which is obtained by encoding a plurality of regions that form image data as units, to obtain the image data, comprising:
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the storage step of storing the encoded data;
the first decoding step of decoding the encoded data stored in the storage step to obtain information associated with a type of region to be decoded;
the discrimination step of discriminating, based on the information associated with the type of region decoded in the first decoding step, if the region is a region of a first type, a quality of which becomes not more than a predetermined quality if the region is compressed at a predetermined compression ratio, or is a region of a second type, a quality of which exceeds the predetermined quality if the region is compressed at the predetermined compression ratio;
the selection step of selecting a decoding method used to decode the region on the basis of the information associated with the type of each region discriminated in the discrimination step; and
the second decoding step of decoding the region by the decoding method selected in the selection step. - View Dependent Claims (58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 74)
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80. An image encoding apparatus comprising:
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input means for inputting image data;
discrimination means for segmenting the image data input from said input means into a plurality of regions, and discriminating a ratio of regions each having a predetermined nature to the image data;
selection means for selecting an encoding method used to compress the region on the basis of a discrimination result obtained by said discrimination means;
first compression means for compressing the region by the encoding method selected by said selection means; and
second compression means for compressing information which helps specify the encoding method used by said first compression means. - View Dependent Claims (81, 82, 83, 84, 85, 86)
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89. An image encoding apparatus comprising:
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determination means for determining an image format of an input image;
attribute discrimination means for discriminating an attribute of the image;
quantization coefficient selection means for selecting quantization coefficients used to encode the image on the basis of the attribute discriminated by said attribute discrimination means, and the image format determined by said determination means; and
encoding means for encoding the image on the basis of the quantization coefficients selected by said quantization coefficient selection means. - View Dependent Claims (90, 91, 92, 93)
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94. An image decoding apparatus for decoding encoded data, which is obtained by encoding an image with a predetermined image format, and information associated with an attribute of the image, to obtain the image, comprising:
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first decoding means for decoding the encoded data to obtain the information associated with the attribute of the image;
attribute discrimination means for discriminating an attribute of the image on the basis of the information decoded by said first decoding means;
dequantization coefficient selection means for reading out the image format of the image, and selecting dequantization coefficients used to decode the encoded data to obtain the image on the basis of the image format and the attribute of the image discriminated by said attribute discrimination means; and
second decoding means for decoding the image on the basis of the dequantization coefficients selected by said dequantization coefficient selection means. - View Dependent Claims (95, 96)
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97. An image encoding method comprising:
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the determination step of determining a type of image format of an input image;
the attribute discrimination step of discriminating an attribute of the image;
the quantization coefficient selection step of selecting quantization coefficients used to encode the image on the basis of the attribute discriminated in the attribute discrimination step, and the type of image format determined in the determination step; and
the encoding step of encoding the image on the basis of the quantization coefficients selected in the quantization coefficient selection step. - View Dependent Claims (98, 99, 100, 101, 105, 106)
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102. An image decoding method for decoding encoded data, which is obtained by encoding an image with a predetermined image format, and information associated with an attribute of the image, to obtain the image, comprising:
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the first decoding step of decoding the encoded data to obtain the information associated with the attribute of the image;
the attribute discrimination step of discriminating an attribute of the image on the basis of the information decoded in the first decoding step;
the dequantization coefficient selection step of reading out the image format of the image, and selecting dequantization coefficients used to decode the encoded data to obtain the image on the basis of the image format and the attribute of the image discriminated in the attribute discrimination step; and
the second decoding step of decoding the image on the basis of the dequantization coefficients selected in the dequantization coefficient selection step. - View Dependent Claims (103, 104, 107, 108)
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Specification