| 摘要 |
<p>PURPOSE:To suppress mosquito noise caused at an increased compression rate when an input picture digital signal is compressed and coded by a DCT(discrete cosine transformation) coder. CONSTITUTION:A picture signal quantized by an A/D converter 11 passes through a 2-dimension low pass filter 12 whose band is set to a pass band and subjected to DCT coding by a DCT coder 13. When an information quantity of the coded signal 18 exceeds a predetermined information quantity, the pass band of the 2-dimension low pass filter 12 is made narrow and when the generated information quantity is less than the prescribed information quantity conversely, the pass band of the 2-dimension low pass filter 12 is set wider. The band of the signal is limited by the 2-dimension low pass filter 12 at an input of a DCT coder 13 in this way, then the production of mosquito noise is suppressed even when the compression rate is increased.</p> |
