 be a lossless or lossy operation. Due depicts a generalized video compression system that im- to the immense volume of video information, lossy plements the spatial and temporal encoding of a digital operations are a key element used in video compression image sequence. Each image in the sequence Ik is defined algorithms. The loss of information or distortion measure as in Eq. (7.4.2). The spatial encoder operates on image is usually evaluated using the mean square error (MSE), blocks, typically on the order of 8 X 8 pixels each. The mean absolute error (MAE) criteria, or peak signal-to- temporal encoder generally operates on 16 X 16 pixel reconstruction noise (PSNR), image blocks. The system is designed for two modes of operation, the intraframe mode and the interframe mode. MSE = The single layer feedback structure of this generalized model is representative of the encoders that are recom- mended by the International Standards Organization (ISO) and International Telecommunications Union MAE = (7.4.2) (ITU) video coding standards MPEG-1, MPEG-2/ H.262, MPEG-4, and H.261 [1, 2, 3, 4]. The feedback loop is used in the Interframe mode of operation and generates a prediction error between the image blocks of PSNR = 2010810(MSE1/2) the current frame and the current prediction frame. The prediction is generated by the motion compensator. The for image I and its reconstructed image I, pixel indices motion estimation unit creates motion vectors for each and 1 image size N X M pixels, and n 16 X 16 block. The motion vectors and previously bits per pixel. The MSE, MAE, and PSNR as described reconstructed frame are fed to the motion compensator here are global measures and do not necessarily give to create the prediction. a good indication of the reconstructed image quality. In The intraframe mode spatially encodes an entire cur- the final analysis, the human observer determines the rent frame on a periodic basis, such as every 15 frames, to quality of the reconstructed image and video quality. The ensure that systematic