Cause and Solution of Checkerboard, Border, and Corner Artifacts of JPEG-XR Compression Algorithm

• Main Authors: Chun-hao Chen, 陳君豪
• Other Authors: Kai-Lung Hua
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/01799245657724451038

碩士 === 國立臺灣科技大學 === 資訊工程系 === 101 === JPEG XR is a still-image compression standard and file format, proposed by Microsoft in 2006. Its encoding process utilizes two types of transform operations: POT (Photo Overlap Transform) and PCT (Photo Core Transform). Using the DPK (Device Porting Kit) provided by Microsoft, we performed encoding and decoding process of JPEG XR on images, and discovered that when the quantization parameter is >1, aka lossy compression conditions, checkerboard block artifacts, border artifacts and corner artifacts can be found in the resulting image. In this paper, we will analyze the cause of the above artifacts. It was found that the main problem lied in the step of POT and quantization. To solve this problem, we will propose the use of a “Normalization Matrix”. After POT (encoding) and before inverse-POT (decoding), we will add an extra step to multiply this normalization matrix. It is an easy and effective way to decrease checkerboard, border, and corner artifacts, thereby improving the image quality of lossy encoding JPEG XR.