Visual Texture Coding Research Articles

SPIHT-Based Coding of the Shape and Texture of Arbitrarily Shaped Visual Objects

A new scheme for coding both the shape and texture of arbitrarily shaped visual objects is presented. Based on set partitioning on hierarchical trees (SPIHT), the proposed Shape and Texture SPIHT (ST-SPIHT) employs a novel implementation of the shape-adaptive discrete wavelet transform (SA-DWT) using in-place lifting, along with parallel coding of texture coefficients and shape mask pixels to create a single embedded code that allows for fine-grained rate-distortion scalability. The single output code simplifies the logistics of object storage and transmission compared to previously published schemes. An input parameter provides control over the relative progression between shape and texture coding in the embedded code, allowing for adjustment of the emphasis of shape versus texture quality in low bit rate reconstructions. The combination of features provided by ST-SPIHT, namely, explicit and progressive shape coding in parallel with wavelet-based embedded coding of the object texture, is unique compared to previously published schemes. Computational complexity is minimized since the shape coding takes advantage of the decomposition and spatial orientation trees used for texture coding. Objective and subjective simulation results show that the proposed ST-SPIHT scheme has rate-distortion performance comparable or superior to MPEG-4 Visual Texture Coding for most bit rates

High performance JPEG 2000 and MPEG-4 VTC on SMPs using OpenMP

JPEG 2000 and MPEG-4 Visual Texture Coding (VTC) are both wavelet-based and state of the art in still image coding. In this paper we show sequential as well as parallel strategies for speeding up two selected implementations of MPEG-4 VTC and JPEG 2000 using the popular shared memory programming paradigm OpenMP. Furthermore, we discuss the sequential and parallel performance of the improved versions and compare the efficiency of both algorithms.

View-Dependent, Scalable Texture Streaming in 3-D QoS With MPEG-4 Visual Texture Coding

Multimedia applications are characterized by high resource demands (computing power, memory, network bandwidth, and power consumption). Efficient implementations aim at reducing these resources to a minimum, which is of the utmost importance for small, low-cost terminals in low-bandwidth networks. Resource savings can also be obtained by content adaptation without impeding the quality of the decoded audio-visual media. In this context, the paper analyzes texture adaptation and streaming for three-dimensional applications, using MPEG-4's Visual Texture Coding tool, in conjunction with eXtensible Markup Language (XML)-based description techniques. Augmented features for content adaptation are supported, such as region selection, accompanied by resolution and SNR settings. As a result, quality is optimized for the terminal's computing capabilities and display resolution, taking the user's viewing conditions into account. Moreover, the instantaneous bandwidth utilization is highly reduced in streaming scenarios.

Perceptual dithering for octave subband image coding

Octave subband coding has been used as an efficient image coding approach for various well-known standards such as MPEG-4 and JPEG-2000. Although the sub-images in the octave subband representation have low statistical correlation, the visual similarity among the sub-images indicates that there exists some unexploited perceptual redundancy between sibling bands in addition to the parent–child redundancy. In this paper, we show that the original image can be perceptually dithered to form a visually equivalent image with increased interband correlation that can be used to achieve more compression. To remove the redundancy among the sibling subbands of an image, we provide a novel perceptual dithering approach that is based on entropy reduction technique with perceptual model. The theoretical basis for the entropy reduction is proven by a theorem for Gaussian distributed signals. The use of our dithering technique is demonstrated for an MPEG-4 compliant encoder with improved coding efficiency using MPEG-4 Visual Texture Coding (VTC) based on zerotree entropy coding. Our results show that there exists a perceptual interband redundancy even though the original interband correlation is small. For a perceptually transparent image quality, our approach can achieve bit savings over MPEG-4 VTC by 11–30% while maintaining compatibility with the MPEG-4 standards.

A Scalable Architecture for MPEG-4 Wavelet Quantization

Wavelet-based image compression has been adopted in MPEG-4 for visual texture coding. All wavelet quantization schemes in MPEG-4—Single Quantization (SQ), Multiple Quantization (MQ) and Bi-level Quantization—use Embedded Zero Tree (EZT) coding followed by an adaptive arithmetic coder for the compression and quantization of a wavelet image. This paper presents the OZONE chip, a dedicated hardware coprocessor for EZT and arithmetic coding. Realized in a 0.5 μm CMOS technology and operating at 32 MHz, the EZT coder is capable of processing up to 25.6 Mega pixel-bitplanes per second. This is equivalent to the lossless compression of 31.6 8-bit grayscale CIF images (352 × 288) per second. The adaptive arithmetic coder processes up to 10 Mbit per second. The combination of the performance of the EZT coder and the arithmetic coder allows the OZONE to perform visual-lossless compression of more than 30 CIF images per second. Due to its novel and scalable architecture, parallel operation of multiple OZONEs is supported. The OZONE functionality is demonstrated on a PC-based compression system.