LOSSLESS VIDEO CODEC HOW TO
The paper elaborates on how to compress a medical video sequence entirely lossless using HEVC.Ĭonsider a typical 16-bit medical X-ray image of UHD resolution that is 3840 pixels by 2160 pixels in resolution. Using prediction and entropy coding tools and with transquant bypass mode enabled lossless compression, a compression ratio greater than 2 can be easily achieved. In addition to Intra and Inter prediction an entropy coding technique CABAC is used for providing better compression. In order to exploit the spatial redundancies HEVC uses Intra prediction and to exploit temporal dependency HEVC uses Inter prediction.
![lossless video codec lossless video codec](https://developer.nvidia.com/sites/default/files/akamai/designworks/images-videocodec/NVENC_HEVC_Tol_T4_P4.png)
In lossless encoding mode, normal predictions are still allowed, so the encoder will find optimal inter or intra prediction and encode the video sequence. Using HEVC, medical video sequence can be encoded entirely lossless. HEVC effectively exploits this temporal and spatial redundancy in order to achieve higher compression ratio. In medical video sequence high temporal and spatial redundancy can be observed. Hence, there is a growing need for medical video compression that will facilitate efficient data transmission, real time tele-consultation and ease of storage. To obtain high image resolution, 16 bits are used to represent a pixel instead of 8 bits, this leads in increased size of medical image. Smallest controllable element of a picture in a medical image is called a pixel. This paper outlines an approach to improve the compression ratio of medical video sequence using HEVC (High Efficiency Video Coding) while satisfying the need of lossless encoding, as usage of lossy compression tools leads to loss of information of the original medical video sequence and may lead to diagnostic errors. This paper outlines lossless encoding mode of HEVC and how using lossless encoding mode, compression ratio of more than 2 (2:1) can be achieved. HEVC encoding can effectively exploit the temporal and spatial redundancy observed in video sequence.
![lossless video codec lossless video codec](http://www.yuvsoft.com/wp-content/uploads/2011/08/lossless_codecs_comparison.png)
Traditional lossless compression technique results in low compression ratio, the goal is to maximize the compression using a lossless compression tool. Hence there is a need to store medical video in lossless format.
![lossless video codec lossless video codec](https://flif.info/img/comparison.png)
Higher compression ratio can be achieved using lossy compression technique, but this will lead to loss of information and may result in diagnostic errors. Today there is a growing need for Medical Video Compression in order to reduce file size on storage requirement. Palachandra M V, Gajanan D Ma Ske (PathPartner Technology)