| 摘要 |
<p>PURPOSE:To secure the prescribed compressibility of picture data while keeping the same extent of quality of restored pictures by setting the upper limit level of frequencies to be cut and cutting all frequencies that exceed the upper limit level in case the high frequencies are adaptively cut. CONSTITUTION:The transformation coefficients F(u, v) are successively stored in a buffer memory, e.g. a FIFO 30 which can store (NXN) pieces of coefficient value from the DC component side. At the same time, the coefficients F are also supplied to a distribution estimating device 40 and a frequency deciding device 80 respectively. The device 80 calculates adaptively the highest frequency (cut-off frequency) C to be handled in a block of the device 80. Then the device 80 calculates the statistic feature value showing the block characteristics for each block and obtains the lower limit value of the number of transformation coefficients to be cut, i.e., a cut-off frequency. Therefore the cut-off frequency also shows the upper limit level of the cut-off frequency.</p> |
