This paper proposes a novel CT image coding concept named LOI which stands for level of interest and coding methods based on that concept. The well-known ROI (region of interest) coding gives priority to pixels in particular regions of an image when encoding or decoding the image. Similarly, LOI coding gives priority to the pixels having a particular pixel level. LOI is ideal for coding of CT images and offers remarkably high coding efficiency. This paper proposes two types of LOI coding methods. One type is the floating point method and the other is the integer method. This paper verifies that the both types improve coding efficiency of pixels in the LOI window. This paper also shows that adequate image quality is obtained even if the viewing window is different from the LOI window.
['Masayuki Hashimoto', 'Kenji Matsuo', 'Atsushi Koike', 'Hiroki Hayashi', 'Tetsuo Shimono']
CT image compression with level of interest