| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technique for suppressing degradation of image quality when coding image data. <P>SOLUTION: A statistical value calculation part 12 specifies macroblocks MB1 to MB8 positioned around an object macroblock MBt and calculates a minimum average value of activities of the macroblocks MB1 to MB8. When the macroblocks MB1 to MB8 are flat and the minimum average value is smaller than an activity of the object macroblock MBt, the minimum average value is set as an adjustment value. A correction factor determination part 13 determines a correction factor Ct on the basis of the adjustment value and a factor determination table 132. By multiplying a reference quantization step value by the correction factor Ct, a quantization step value Qt of the object macroblock MBt is determined. Since the quantization step value Qt reflects the distribution of the activities of the macroblocks MB1 to MB8, it is possible to suppress a local change of the quantization step value Qt. <P>COPYRIGHT: (C)2011,JPO&INPIT |
