| 摘要 |
PURPOSE:To improve picture quality by restoring a contour with fidelity and to heighten compressibility, by interpolating between the picture element of a predicted origin and that of a time difference value at the time of expanding and interpolating a data. CONSTITUTION:At a transmission side, a first-order difference between lines is compressed 3 by the variable sample density encoding of a second-order difference in a line direction. At a reception side, the first-order difference between the lines is restored at a variable sample density expansion circuit 8 by a quantization characteristic and an interpolation table, and is stored in a line buffer 9, and it is added 11 on the restored value of a preceding line in a line buffer 12, then, the restored value of a current line can be obtained. Therefore, in a case that an amplitude difference value of a quantization point in which the amplitude difference value does not arrive at a minimum value except (0) with the same time difference value is interpolated with a ratio of 1/2 at every reduction by (1) of the sample interval, the quantization point is set so that an interpolation value becomes smaller than the minimum amplitude difference value with the time difference value at the time of reducing the sample interval by (1), and the quantization point in a section smaller in the time difference value is interpolated.
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