| 摘要 |
PURPOSE:To prevent the deterioration such as a block distortion from being conspicuous at a restored picture quality by compressing the level of input data and thereafter, processing such as encoding when the prepared information quantity becomes much. CONSTITUTION:By a blocking circuit 3, an input digital video signal is converted to a continuous signal for a two-dimensional block which is the unit of encoding, and supplied to a maximum value detecting circuit 4, a minimum value detecting circuit 5 and a delaying circuit 6. A dynamic range DR, which is the difference between the detected maximum MAX and the minimum value MIN, is obtained from a subtracting circuit 7. For an encoding circuit 22, a threshold set Ti from a threshold determining circuit 9 and the dynamic range DR from a subtracting circuit 20 are supplied, and the ADRC encoding of the variable length to quantize data PDI is executed. Thus, even when the data are quantized by the number of the bits of a 0 bit, 1 bit, 2 bits, 3 bits or 4 bits smaller than 8 bits, the quantization distortion is not conspicuous. |
