文档介绍：1预测技术( Prediction ) 范晓鹏 ******@hit. 哈工大软件学院联通班 2011 年春季《数据压缩技术》课程第二讲 2主要内容?预测技术( 2学时) –预测编码–视频压缩中的预测技术 3 Lossless Predictive Coding ? Predictive technique ? Makes use of correlation between neighboring values – In typical images values of adjacent pixels are highly correlated – In typical audio values of adjacent samples are highly correlated (speech consists of mainly silence) ? DPCM (Differential Pulse Code Modulation): Most Common form of Lossless Predictive Coding 34 Lossless DPCM: General Procedure ? Use values of neighboring pixels to predict value of the current pixel. – Idea is to remove any structure that might exist. ? Find the difference between the actual and predicted values – Difference also called Error / Residual ? Encode the Residual 45 Lossless DPCM Encoder 5 Predictor entropy coder - mmmxxe ??? mx mx ? me6 Lossless DPCM Decoder 6 entropy decoder + Predictor m m mxex ??? mx ? me me7 7 Prediction/Differential Coding Outline ? Predict Pixel value based on Neighboring Pixels ? Find the Error (Residual) – Residual = Original – Predicted Value ? Quantize Error ? Encode Quantized Error 8 8 Pixel Prediction A BCX Pixel being predicted X = a · A + b · B + c ·C A,B,C : Pixel Values a, b, c: Prediction Coefficients 9 9 Distribution of Values in Original and Residual Images 10 10 Distribution of Values in Original and Residual Images