| abstract |
In PCM and DPCM systems, a Hadamard orthogonal transformation of picture element signals is known to offer a means for reducing the bit rate for transmission of the signals. The first Hadamard coefficient, called H 1 , equals the sum of the picture element signals. Accordingly, still further reduction in the transmission bit rate can be achieved by efficiently coding H 1 . The disclosed coder includes a control signal generator for providing a control signal corresponding to a predetermined function of the quantized Hadamard coefficient signals. Several illustrative arrangements are disclosed. In three arrangements, the respective control signals are employed to adaptively select one of a plurality of quantizers, the selected quantizer for coding H 1 . In a fourth arrangement, the control signal is employed to predict H 1 , the predictor control signal being thereafter used for coding H 1 . |