| 摘要 |
In a quantizing method, a quantizing apparatus, and a coding method, and also a coding apparatus, an error between data dequantized by a decoder and a DCT coefficient of an encoder can be minimized. A DCT circuit compresses an image signal to produce a DCT coefficient corresponding to this image signal, and outputs this DCT coefficient to a quantizing unit. A quantizing circuit of this quantizing unit converts the DCT coefficient into intermediate data by utilizing a first quantizing scale, and calculates an average value of the intermediate data in a predetermined range from an occurrence probability distribution of the intermediate data. Further, the quantizing circuit 11 calculates a second quantizing scale from this average value and the first quantizing scale. This quantizing circuit 11 converts the DCT coefficient into another intermediate data by using the second quantizing scale. A representative value circuit 12 converts the intermediate data within a predetermined range into such a value that a value dequantized by the second quantizing scale becomes the above-described average value, and also outputs both the second quantizing scale and such a value that the dequantized value becomes a reference value to a variable length coding device.
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