A study of Influence of compression Technology on Multi-spectral Image Quality

• Main Authors: Ting-Yun Lin, 林婷筠
• Other Authors: M. James Shyu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/71056254869469178958

碩士 === 中國文化大學 === 資訊傳播學系 === 99 === The problem of metamerism is commonly seen in color reproduction by regular tri-chromatic (RGB) camera, where color-matchings can appear differently under different conditions. This problem can be solved by multi-spectral image technology by processing object’s spectral reflectance. Multi-spectral image uses higher color fidelity than RGB image so it takes up much more memory space than regular tri-chromatic image. This study adopts JPEG and JPEG2000 compression algorithms to produce fourteen kinds of compress methods in three kinds of combination: selecting one or two dimensional slicing, using DCT or DWT transformations, selecting threshold or quantification methods. At first stage, a GretagMacbeth Mini ColorChecker was used as the index to pick the better six compression methods by having smaller color difference values before and after compression. Secondly, these six compression methods were compared by using six multi-spectral images captured from a spectral camera and were reduced to three kinds of compression methods having lower averaged color difference. In this study, the color difference values were used as a primary index to determine the quality of a compression method. Meanwhile, PSNR and MSE were also calculated for references. The results indicate that a compression rate of 8 to 10 can be achieved for color difference value less than 1 when using one dimensional compression method. A compression rate of 30 to 50 can be achieved when using two dimensional compression method. All the PSNRs are higher than 35 and MSEs are below 3.0E-4 below for the final 3 compression methods.