| 摘要 |
PURPOSE:To reduce deterioration in picture quality attended with roughness of a quantization step effectively without increasing the number of bits of each code by quantizing a signal with a different quantization characteristic from each picture and increasing the number of quantization levels to the same picture element as to plural patterns consecutive in time base in a simulating way. CONSTITUTION:A coder consists of an input terminal 30, a subtractor 32, quantizers 34, 36, signal changeover switches 38, 46 an output terminal 40 for coding code, inverse quantizers 42, 44, an adder 48, an input terminal 50 for a frame ID signal, a limiter 52, and a prediction device 54. Then plural quantizers 34, 36 with a different quantization characteristic are used for each pattern sequentially and the picture information is coded. Since the border value of the quantization characteristic of the plural quantizers 34, 36 differs from each other except at the quantizing range ends, the quantization level number is plural number of multiple in a pseudo way. Thus, the deterioration in the picture quality attended with roughness of the quantization step is reduced effectively without increasing the bit number of each code. |
