09-05-2011, 02:44 PM
IMAGE COMPRESSION USING WEDGELETS.ppt (Size: 635.5 KB / Downloads: 98)
IMAGE COMPRESSION USING WEDGELETS
INTRODUCTION
IMAGE COMPRESSION
NEED OF COMPRESSION
THE PRINCIPLES BEHIND COMPRESSION
Typical image coder
JPEG : DCT-Based Image Coding Standard
Wavelet Coder
Need of Wavelet-based Compression
Geometry Based Technique
WEDGELETS
The Wedgelet Dictionary
Wedgelet Estimation
THE WEDGELET DICTIONARY
a)Parameterization of a wedgelet on an N*N image block
orientation θ ,offset d & grayscale intensity values m1, m2
b)Example of a wedgelet for pixelized image block, N=16
a) Artificial Image
b) Wedgelet decomposition. Each dyadic
block in the tiling is constant or contains
a single straight line.
COMPRESSION VIA EDGE CARTOON
ESTIMATION AND COMPRESSION OF THE EDGE CARTOON
Pruned wedgelet quadtree.
Interior nodes I, Leaf nodes E (edge) and C (contant).
The cartoon sketch is drawn according to leaf nodes.
Cartoon sketch C obtained from the coded wedgelet parameters. (Blocking artifacts at the wedgelet borders).
Final coded cartoon sketch C . Smoothing removes blocking artifacts while preserving coded edge.
Residual Texture Image
Wavelet compressed residual image coded cartoon sketch PSNR 28.48db
ZEROTREE COMPRESSION