3-D medical image compression using 3-D wavelet coders

This paper presents compression of 3-D medical images using 3-D wavelet encoders. Four wavelet transforms, namely, Daubechies 4, Daubechies 6, Cohen–Daubechies–Feauveau 9/7 and Cohen–Daubechies–Feauveau 5/3 are used in the first stage with encoders such as 3-D SPIHT, 3-D SPECK and 3-D BISK used in the second stage for the compression and the optimal wavelet–encoder combination is identified. Two versions of wavelet transform, symmetric and decoupled wavelet transform are considered. Experiments are performed using medical test images such as magnetic resonance images (MRI) and X-ray angiograms (XA). The performances of the proposed scheme are evaluated in terms of peak signal-to-noise ratio and bit rate. Further mean structural similarity (MSSIM) index is introduced to evaluate the structural similarity between the original and the reconstructed images. It is found from the test results that the 3-D Cohen–Daubechies–Feauveau 9/7 symmetric wavelet along with the 3-D SPIHT encoder yields the best compression result.