Efficient Huffman Decoding Aggarwal, M. and Narayan, A., International Conference on Image Processing, vol. 1, pp. 936 – 939, 2000 Presenter :Yu-Cheng Cheng

Outline Introduction The Decoding Algorithm Discussion and Conclusions

Introduction Huffman codes are being widely used in image and video compression. The paper has proposed a two-step algorithm to decode Huffman codes.

Outline Introduction The Decoding Algorithm Discussion and Conclusions

The Decoding Algorithm The first step, the subset or partition corresponding to the leading codeword is determined. The paper defines a function lmbc(), which takes a sequence of bits as input and returns the position of the first-bit-change starting from the leading bit.

The Decoding Algorithm Fig.1 The Huffman tree of codewords

The Decoding Algorithm Table 1. Huffman Table

The Decoding Algorithm Example, consider the bitstream B = which corresponds to gbpc.

The Decoding Algorithm The paper notes that the codewords in a particular partition of Table 1 need not have the same length. The paper creates a one-dimensional array actlen.

The Decoding Algorithm Table 2. Modified Huffman Table

The Decoding Algorithm Fig. 2. The decoding data structures

Outline Introduction The Decoding Algorithm Discussion and Conclusion

Discussion and Conclusions The proposed algorithm requires very few computations to decode a codeword, and the complexity is independent of the height h of the Huffman tree.