| 摘要 |
<p>PURPOSE: To easily execute discrete cosine transformation with plural predetermined transformation coefficients for a transformation input value. CONSTITUTION: Frequency N1 of shifting operation is determined so that a series of N1 times of shifting operations are required regardless of the transformation input value. The frequency N2 of addition operations is determined so that a series of N2 times of the addition operations is required regardless of the transformation input value. An output value of the discrete cosine transformation is determined by executing N1 times of the shifting operations and N2 times of the addition operations for the transformation input value. This method is applicable to the discrete cosine transformation in both forward and backward directions. The transformation coefficients are simplified coefficients obtained by discarding or correcting conventional transformation coefficients. In this simplification, the coefficients are calculated so that the shifting and the addition operations to calculate an approximation of the product of multiplication by the coefficients are below a specific frequency. Quality degradation of video image transformed by using the simplified coefficients is brought about by the simplification of the coefficient. Therefore, the simplification is suppressed so that the degradation of the image is within an allowable limit.</p> |
