Signal processing for joint source channel coding of digital images

An example of arithmetic coding : The source symbols are a, b, c with p(a) = 0.011, p(b) = 0.011, p(c) = 0. Wavelet coefficients of test images. Subbands are independently scaled. Most energy is concentrated in the low frequency (upper-left) subbands and a few coefficients in other subbands (in the locations of edges).. 2.6 (a)-A factor graph for a [6, 3, 3] binary code C. Function nodes are drawn as small filled circles and variable nodes are drawn as larger non-filled circles.The global function f (x) = 3 i=1 f i (x (i)) = 1 if x is a word in C and f (x) = 0 otherwise. The local functions f i (x (i)) are equal to 1 if the length three vectors x (i) have even weight and equal 0 otherwise. For example, f 1 (x (1)) ≡ f 1 (x 1 , x 2 , x 6) = (x 1 + x 2 + x 6) mod 2. (b)-A factor graph for a posteriori distribution of a [6, 3, 3] binary codeword transmitted over a memoryless channel. Additional functions f jj are channel likelihoods evaluated at the observed values of y