A low memory QCB-based DWT for JPEG2000 coprocessor supporting large tile size

Abstract

JPEG 2000, which provides a higher compression ratio than the traditional JPEG, is an upcoming compression standard for still images. The experimental results imply that larger tile size used for JPEG 2000 results in better image quality. However, processing the large tile image requires more memory in the hardware implementation. To reduce the hardware resources, a QCB (quad code-block)-based DWT method is proposed to support the process of large tile image with low memory. Based on the QCB-based DWT engine, three code-blocks belonging to LH(0), HL(0) and HH(0) bands can be generated after each fixed time slice recursively and the EBC (embedded block coding) processors can directly process the three code-blocks. It can save the size of tile memory up to 75%. Moreover, the remaining 1/4 size of tile memory can be decreased through the zero holding extension for the unavailable data. That is, it only requires 24K bytes memory to support the process of 512x512 tile image, with slight image degradation, especially at low bit rates. The low memory requirement makes the hardware implementation practicable.