PERCEPTUAL QUANTITATIVE QUALITY ASSESSMENT OF JPEG2000 COMPRESSED CT IMAGES WITH VARIOUS SLICE THICKNESSES

Modern medical equipments produce huge amounts of data that need to be archived for long periods and efficiently transferred over networks. Data compression plays an essential role in reducing the amount of medical imaging data. Medical images can usually be compressed by a factor of three before any degradation appears. Higher compression levels are desirable but can only be achieved with lossy compression, thus scarifying image quality. The diagnosis value of compressed medical images has been studied and recommendations about maximum acceptable compression ratios have been provided based on qualitative visual analysis. It has been suggested, without further investigation, that CT images, with thicknesses below five mm, cannot undergo lossy compression if diagnostic value needed to be preserved. In this paper, we present an objective quantitative quality assessment of compressed CT images using Visual Signal to Noise Ratio. Our results show that visual fidelity can be significantly affected by two factors, slice thickness and exposure time, for images compressed using the same compression ratio.