22-08-2014, 09:54 AM
Data size is meaningful at the time of data transfer. So we have to reduce the size of data.Two main algorithm are used to compress the data. They are lossy compression technique and lossless compression technique. JPEG (Joint Photographic Expert Group) is one type of lossy technique. JPEG is based on DCT(Discrete Cosine Transform). Another version of JPEG is JPEG 2000 which works as lossy as well as lossless. JPEG 2000 includes a lossless mode based on a special integer wavelet filter. Lossless JPEG was developed as a late addition of JPEG. It uses a predictive scheme based on three nearest (casual), neighbors (upper, left and upper-left), and entropy coding is used on the prediction error. JPEG-LS is nearly lossless technique based on LOCO algorithm.
Four dimensional (4D) medical data are sequences of volumetric images captured in time. These data sets are typically very large in size and demand a great amount of resources for storage and transmission. Our lossless compression technique efficiently exploits spatial and temporal redundancies between 2D image slices and 3D images in 4D medical images and eliminates any concerns regarding the effects of compression on image quality for diagnostic purposes. Performance evaluations have shown that the proposed compression technique outperforms current 4D compression methods by 70%.