Quality controlled ECG compression using Discrete Cosine transform (DCT) and Laplacian Pyramid (LP)

Abstract

This paper introduces a new quality controlled Discrete Cosine transform (DCT) and Laplacian Pyramid based compression method for electrocardiogram (ECG) signal. The ECG signal is transformed using DCT and Laplacian Pyramid. The transformed coefficients are thresholded using the bisection algorithm in order to match the predefined user specified percentage root mean square difference (PRD) within the tolerance. Then, the binary lookup table is made to store the position map for zero and non-zero coefficients (NZC). The NZC are quantized by Max-Lloyd quantizer followed by Arithmetic coding. Lookup table is encoded by Huffman coding. The results are presented on different ECG signals of varying characteristic. The results show that DCT gives better performance at low PRD. The results show that Laplacian Pyramid provides better CR over 2.5 PRD value on the normal rhythm (MIT-BIH 117) as compared to DCT, whereas on abnormal rhythm (MIT-BIH 232) the behavior of the transforms is opposite.