| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve color unevenness and color migration under low illumination and high illumination. <P>SOLUTION: A component conversion apparatus 51 converts multiplexed data into 3 components of luminance and 2 color differences. Tile-dividing apparatuses 52a and 52b divide 1 frame into small regions (tile), band dividing apparatuses 53a and 53b divide frequency bands. A nonlinear color signal processing apparatus 57 discriminates the illumination of an object from output data of the device 53a, and in a case of low illumination or high illumination, adjusts a quantization step of quantizing apparatuses 54a and 54b. For example, at low illumination, quantization step width of a high-frequency side conversion coefficient in the color difference data components, is made larger than normal, and corresponding to this, the quantization step in a high-frequency component in illumination data is corrected. However, information of the quantization step width which is adjusted will not be transmitted. The quantization apparatuses 54a and 54b quantize the outputs of the apparatuses 53a and 53b in the established step width. An entropy-encoding circuit 55a and 55b encode the outputs of the apparatuses 54a and 54b. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
