| 摘要 |
In a Hadamard transform coding device, input image signals are first subjected to Hadamard transform. After the Hadamard transform, the DC coefficients are subjected to variable-length coding, and the AC coefficients are subjected to variable-length coding after the output of an AC coefficient predictor is subtracted therefrom. The AC coefficient predictor predicts the AC coefficients of a center block on the basis of the DC coefficients of the adjacent blocks. In a Hadamard transform decoding device, the DC coefficients are first subjected to variable-length decoding. An AC coefficient predictor predicts the AC coefficients of the center block on the basis of the DC efficient of the adjacent blocks. Thereafter, the AC coefficient prediction error is subjected to variable-length decoding, and added with the output of the AC coefficient predictor to obtain the AC coefficients. The transform coefficients thus obtained are subjected to Hadamard inverse-transform to obtain image signals.
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