Television – Bandwidth reduction system – Data rate reduction
Patent
1993-03-11
1994-04-26
Hjerpe, Richard
Television
Bandwidth reduction system
Data rate reduction
358432, 382 56, 348420, 348390, H04N 712
Patent
active
053071638
ABSTRACT:
A coding apparatus, in which each block having a plurality of picture elements with digital image signals is divided into a plurality of sub-blocks, and an appropriate quantization step or weighting factor is decided on the basis of the absolute value sum of difference of image signal level between adjacent picture elements in the sub-block, so that a digital image signal is reduced. Moreover, a coding apparatus, in which each block having a plurality of picture elements with digital image signals is divided into a plurality of sub-blocks, and an appropriate quantization step or weighting factor is decided on the basis of the maximum and minimum values of the image signals of the picture elements in the sub-block, so that a digital image signal is reduced. Accordingly, in the coding apparatus as above, the state of the image is recognized for every block, whereby a block whose degradation of image quality is hard to notice at the decoder side is quantized or subjected to weighting with low rate, that is, with large reduction rate, whereas a block whose degradation of image quality is conspicuous at the decoder side is quantized or subjected to weighting with high rate, i.e., with small reduction rate. As a result, the image quality of the background having little change in the signal is kept good.
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S. M. C. Borgers et al., "An Expt. Digital VCR with 40 Drum, Single Actuator & DCT-Based Bit-Rate Reduction", vol. 34, No. 3.
Signal Processing of HDTV, Proceedings of the Second International Workshop on Signal Processing of HDTV, L'Aquila, 29th Feb.-2nd Mar. 1988, pp. 231-238.
Asamura Yoshinori
Hatano Yoshiko
Onishi Ken
Hjerpe Richard
Mitsubishi Denki & Kabushiki Kaisha
Oh Minsun
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