Spatially Continuous Orientation Adaptive Discrete Packet Wavelet Decomposition for Image Compression

Abstract

In this paper, we propose an orientation adaptive discrete wavelet transform (DWT) with perfect reconstruction. The proposed transform utilizes the lifting structure to effectively orient the 2D-DWT bases in the direction of local image features. A shifting operator is employed within each lifting step to align spatial geometric features along the vertical or horizontal directions. The proposed oriented transform generates a scalable representation for the image and the orientation information. To approximate the asymptotically optimal rate-distortion performance of a piecewise regular function more closely, we adopt a packet wavelet decomposition. The experimental results obtained by implementing the proposed transform in a JPEG2000 codec illustrate superior compression performance for the oriented transform with more than 2.5 dB improvement for highly oriented natural images. More importantly, even at the same PSNR, the proposed scheme reduces the visual appearance of the Gibbs-like artifacts significantly, considerably improving the visual quality of the reconstructed image.

Modeling of contours in wavelet domain for generalized lifting image compression

“…As correlation persists, large magnitude coefficients that usually represent contours remain spatially co-located. Decorrelation of these coefficients to minimize their energy is of particular interest in wavelet-based image coding [1][2][3][4][5]12].…”

Space-Frequency Quantization for Image Compression With Directionlets

“…In addition, the method in [13] uses the pixel values at fractional coordinates obtained by interpolation. Lifting is also implemented in [10] and in [15], where the wavelet packet decomposition is applied. However, even though these methods are computationally efficient and provide good compression results, they show a weaker performance when combined with zerotree-based compression algorithms.…”

Generalized Lifting with adaptive local pdf estimation for image coding

“…As correlation persists, large magnitude coefficients representing contours remain spatially colocated. As a result, current research efforts are focusing on the design of schemes able to decorrelate these coefficients or to minimize their energy [1][2][3][4][5]11].…”