A scalable architecture for MPEG-4 wavelet quantization

Wavelet-based image compression has been adopted in MPEG-4 for visual textu re coding. All wavelet quantization schemes in MPEG-4-Single Quantization ( SQ), Multiple Quantization (MQ) and Bi-level Quantization-use Embedded Zero Tree (EZT) coding followed by an adaptive arithmetic coder for the compres sion and quantization of a wavelet image. This paper presents the OZONE chi p, a dedicated hardware coprocessor for EZT and arithmetic coding. Realized in a 0.5 mu m CMOS technology and operating at 32 MHz, the EZT coder is ca pable of processing up to 25.6 Mega pixel-bitplanes per second. This is equ ivalent to the lossless compression of 31.6 8-bit grayscale CIF images (352 x 288) per second. The adaptive arithmetic coder processes up to 10 Mbit p er second. The combination of the performance of the EZT coder and the arit hmetic coder allows the OZONE to perform visual-lossless compression of mor e than 30 CIF images per second. Due to its novel and scalable architecture , parallel operation of multiple OZONEs is supported. The OZONE functionali ty is demonstrated on a PC-based compression system.