Parallel Wavelet Schemes for Images
This work addresses efficiency improvements for image compression tasks, particularly in JPEG 2000, but is incremental as it builds on existing wavelet transform methods.
The paper tackles the problem of reducing synchronization overhead in parallel discrete wavelet transforms for images, achieving a reduction to only two memory barriers for the 2-D CDF 5/3 transform compared to four in the original method.
In this paper, we introduce several new schemes for calculation of discrete wavelet transforms of images. These schemes reduce the number of steps and, as a consequence, allow to reduce the number of synchronizations on parallel architectures. As an additional useful property, the proposed schemes can reduce also the number of arithmetic operations. The schemes are primarily demonstrated on CDF 5/3 and CDF 9/7 wavelets employed in JPEG 2000 image compression standard. However, the presented method is general, and it can be applied on any wavelet transform. As a result, our scheme requires only two memory barriers for 2-D CDF 5/3 transform compared to four barriers in the original separable form or three barriers in the non-separable scheme recently published. Our reasoning is supported by exhaustive experiments on high-end graphics cards.