| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a methods and an apparatus for coding and decoding images, considering the visual characteristics of human beings. <P>SOLUTION: A coding method for images is composed comprising, (a) a step of modeling an image quality distribution of an input image inputted by a unit of a screen in an image quality modeling portion 140 so that the quality of the input image inputted by the unit of a screen, gradually lowers from a target region towards the background region, (b) a step of determining quantization coefficients of each region which forms a screen on the basis of a modeling result of the image quality distribution, (c) a step of quantizing image data in an adaptive quantizing portion 155 on the basis of the quantization coefficients determined in stage (b), and (d) a step of coding the entropy of the quantized image data in an entropy coding portion 160. A screen is divided in to a target region and the background region by this method, and subjective image quality can be enhanced by performing modeling so that image quality does not change suddenly but changes gradually between both regions. <P>COPYRIGHT: (C)2004,JPO |
