发明名称 |
Apparatus for encoding an image signal |
摘要 |
Apparatus for encoding an image signal which is capable of improving the quality of a reproduced image with respect to not only a general image in which electric power is concentrated in low-frequency region coefficients but also an image where the electric power is concentrated in a high-frequency region. The apparatus comprises a blocking device in which a rectangular area in an image is detected from a digital image signal as a pixel block, and is subjected to an orthogonal transform by a converter to obtain a transformed coefficient. In addition, an activity calculator calculates the variance of the image within the block, and electric power to be preserved during encoding is determined by a power-preservation-rate determining device on the basis of the variance determined. An optimum mask is selected by a mask selector on the basis of a transformed coefficient from the converter and a power preservation rate from the power-preservation-rate determining device, and the selection of the transformed coefficient is performed by a coefficient selector by means of this mask. The transformed coefficient after being selected is quantized by a quantizer, is encoded to be outputted through a transmission line.
|
申请公布号 |
US5598484(A) |
申请公布日期 |
1997.01.28 |
申请号 |
US19950385204 |
申请日期 |
1995.02.08 |
申请人 |
FUJI XEROX CO., LTD. |
发明人 |
SUZUKI, KAZUHIRO;KAMIZAWA, KOH;KOSHI, YUTAKA;KUNITAKE, SETSU |
分类号 |
G06T9/00;H04N7/26;H04N7/28;H04N7/30;(IPC1-7):G06K9/36;G06K9/46 |
主分类号 |
G06T9/00 |
代理机构 |
|
代理人 |
|
主权项 |
|
地址 |
|