PURPOSE: To prepare easily visible video images whose degradation is hardly detected by the eyes of humans while suppressing the increase of the information amount of the entire video images by giving weight corresponding to brightness and darkness and changing the quantization of inputted digital video signals.
CONSTITUTION: The video signals inputted from an input terminal 1 are blocked into the blocks of 8 picture elements ×8 lines for instance in a block shuffling circuit 2 and shuffling is performed by the unit of the blocks or the unit of macroblocks constituted of the plural blocks. Signals outputted from the circuit 2 are inputted to a converter I 11 and the converter I 11 outputs the luminance signals of 9 bits and the chrominance signals of 8 bats as they are. The signals are inputted to a DCT circuit II 12 subjected to discrete cosine transformation and turned to DCT coefficients. The DCT coefficients are inputted to a control circuit 4 and a quantization circuit 5 and the circuit 4 controls the quantization circuit 5 so as to perform the quantization with a prescribed block number. Data for which the DCT coefficients quantized in the circuit 5 are variable- length encoded in an encoding circuit 6 are stored in a buffer memory I 7 and outputted from an output terminal. 8 at a fixed rate.
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KURAHASHI SOJI
HIBI TAKETOSHI
ONISHI TAKESHI
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