Block-Adaptive Discrete Cosine Transform with Rate-Distortion Control

• Main Authors: Lee, Shiuh-Ming, 李旭明
• Other Authors: Long-Wen Chang
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/76454073717365139363

碩士 === 國立清華大學 === 資訊工程學系 === 86 === Block-Adaptive Discrete Cosine Transform with Rate-Distortion ControlDiscrete Cosine Transform (DCT) has been used for many image or video coding standards such as JPEG, H.261/3, MPEG-1/2/4, etc. In this paper, a block adaptive DCT coder by using a quadtree-based variable blocksize DCT is proposed. It can achieve the best trade-off between the bitrate and the image quality by using the Lagrange multiplier λ merge rate and distortion. By using the quantization matrix generated by the visual model, our performance has a significant improvement on image quality. Simulation resultsshow that our coding scheme outperforms the standard JPEG coder about 1-2 dB at typical bit rates. It can compete with other coding schemes like embedded zerotree wavelet (EZW) and embedded zerotree DCT(EZDCT).