Patent ID: 7649940

Claim:
An image coding apparatus for coding an image in a unit of a block, characterized in that said image coding apparatus comprises: first arithmetic operation means for calculating a value of a first parameter representative of complicacy of the block; second arithmetic operation means for calculating a variance of value of a second parameter representative of complicacy of the block; storage means for storing the variance of the value of the second parameter calculated by said second arithmetic operation means; and third arithmetic operation means for calculating a range of a quantization index of the block based on the value of the first parameter and the variance of the value of the second parameter stored by said storage means, wherein the range of the quantization index varies in accordance with a coefficient value calculated discretely based on the range of the variance of the motion vector residuals, such that when the coefficient value is 1, the range of the quantization index is a constant and when the coefficient value is greater than 1 the range of the quantization index is between the coefficient value and the reciprocal of the coefficient value, and wherein said third arithmetic operation means calculates the range of the quantization index discretely based on the range of the variance of the motion vector residuals such that the coefficient is predetermined as calculated from the variance of the motion vector residuals within a fixed range as a fixed value.