In this paper, we describe a robust method for the extraction of the apparent 3-D camera velocity and 3-D scene structure information. Our method performs the extraction of the apparent 3-D camera velocity in a fully automated way without any knowledge about 3-D scene content information as used in current methods. This has the advantage that it can be used to fully automate the generation of natural-looking virtual/augmented environments, as well as in video-database browsing. First, we describe our method for the robust extraction of 3-D parameters. This method is a combination of the eight-point method in structure-from-motion with a statistical technique to automatically select feature points in the image, irrespective of 3-D content information. Second, we discuss two applications which use the results of the 3-D parameter extraction. The first application is the generation of sprite layers using 3-D camera velocity information to represent an eight-parameter perspective image-to-sprite mapping plus 3-D scene depth information for the sprite layering. The second application is the use of 3-D camera velocity for the indexing of large video databases according to a set of seven independent types of camera motion. In this application, we discuss a formal video description structure-the camera-motion descriptor-which was successfully included in the working draft of the MPEG-7 video standard.

We describe the MPEG2 4:2:2 Profile and present a study of its characteristics. The MPEG2 4:2:2 Profile provides a conformance point that addresses, among other applications, the needs of the professional studio and post-production environment, and that provides interoperability. The requirements of such an environment for compressed digital video together with a functional description of the 4:2:2 Profile are given. The 4:2:2 Profile provides a flexible compression solution that allows editability, supports a wide range of bit rates, and provides good to excellent quality in both an intra and interstudio environment. Our experiments show that the 4:2:2 Profile is very robust in a multigeneration environment, provides an efficient coding solution for transmission and storage, and provides transparency or near transparency in chroma keying operations. In addition, it compares favorably with existing digital compression standards, such as Motion-JPEG, and is superior to widely used analog technology.

A new image-coding algorithm that exploits the relationship between various subbands of an image is presented in this correspondence. Using local variance for state selection and uniform threshold quantizers on subbands, we have achieved a reduction in quantization noise compared to other published techniques for Lena at various bit rates.

Multiresolution transmission of compressed video is performed using subbands. Multistage quantization is necessary for efficient embedded video transmission on rate constrained channels. This paper investigates the performance of a number of multistage scalar quantization techniques: concatenated coding, conditional entropy coding and conditional quantization. Intraframe as well as interframe coding approaches are investigated with these multistage quantization techniques on high definition and standard definition source material.>

Several methods to perform multiresolution transmission of HDTV through subband coding are compared. The first is simple intraframe encoding of the spatial subbands of the video. The authors have used the subband decomposition for both hierarchical estimation of the motion as well as encoding of the compensated error function. They have used block matching for motion estimation on both 2D lowpass and bandpass (QMF) pyramids. They found that the motion estimation on the lowpass QMF pyramid performs better than the motion estimation on the bandpass QMF pyramid. They achieved approximately the same quality reconstructed video with either backward or forward motion compensated schemes. For multiresolution transmission, by simulating a test sequence, they have obtained a PSNR of 35 dB at the bit rate of 0.44 bits per pixel with adaptive PCM and at a bit rate of 0.53 bits pet pixel with PCM. Such a result would require 0.75 bits per pixel for the intraframe scheme. The complexity of the motion compensated multiresolution coding scheme is comparable to that of a single resolution method.>

Recently, Uz et al. (ibid., vol.1., no.1, p.86-99, 1991) analyzed the propagation of quantization noise in a pyramid (with feedback) and subband decomposition schemes. In this study each band was independently quantized by a scalar quantizer of equal step size. The resulting reconstruction error spectrum indicated that in both the pyramid (without feedback) and subband coding schemes, noise was building up in lower frequencies. The commenters show that a quantizer assignment method, using mean-square-error (MSE) optimal bit allocation, avoids the problem. The authors argue that the problem is more involved than just MSE optimal bit allocation, and that compatible coding was the focus, as well as guaranteed quality, effects of numerical computations, and perceptual effects. The commenters further support their argument.>

The authors compare the subband compression capabilities of eight filter sets (consisting of linear-phase quadrature mirror filters (QMFs), perfect reconstruction filters, and nonlinear phase wavelets) at different bit rates, using-a filter-based bit allocation procedure. Using DPCM and PCM in HDTV subband coding, it is found that QMFs have an edge over the rest.