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Compression: directionlets + zerotrees


For more details check this publication.


      

Standard zerotrees are adapted to directionlets. The children at finer scales are grouped in anisotropic and oriented clusters.




Numeric compression results obtained using the standard wavelet transform and directionlets and shown for two images: Lena and Barbara. The results are shown for very low bit-rates (< 0.2bpp). The gain is significant (> 1dB).



    

The image Lena is compressed at the bit-rate 0.0395bpp using the two methods. The reconstructions have PSNR = 23.51dB and 26.07dB, respectively. The artifacts in the reconstruction obtained by directionlets are aligned with local dominant orientations in the image and are less visually perceptible.