On improving the performance of multiplierless DCT algorithms

This paper investigates a number of issues having an impact on the performance of an approximated multiplierless DCT, which include: types of inverse transforms; types of normalizations; algorithm structures; and assignment of signed digits for approximating constants. Based on our experiment results, we have the following findings: (1) a transform based on a reversible inverse generally performs better than a version based on a traditional inverse; (2) a transform with a delayed or post normalization can achieve a much better performance; (3) uniform normalization can be considered a useful feature; (4) a lifting structure transform can achieve better accuracy than a non-lifting structure version; (5) an optimized configuration for the assignment of signed digits to the constants could help to boost the performance of the approximated DCT. It is believed that such findings should provide useful insights into making the proper design choices when converting a fast DCT into a multiplierless version.