Thumpudi Naveen

Description of shape information for 2-D and 3-D objects

The description of the spatial characteristics of two- and three-dimensional objects, in the framework of MPEG-7, is considered. The shape of an object is one of its fundamental properties, and this paper describes an efficient way to represent the coarse shape, scale and composition properties of an object. This representation is invariant to resolution, translation and rotation, and may be used for both two-dimensional (2-D) and three-dimensional (3-D) objects. This coarse shape descriptor will be included in the eXperimentation Model (XM) of MPEG-7. Applications of such a description to search object databases, in particular the CAESAR anthropometric database are discussed.

Motion compensated multiresolution transmission of high definition video

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. >

Apparent 3-D camera velocity-extraction and applications

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.

MPEG-2 4:2:2 profile at main level: an emerging high-quality video compression standard

In this paper we describe the MPEG2 4:2:2 Profile @ Main Level (abbreviated to 422@ML), and present a study of its characteristics. The MPEG2 422@ML provides a standard based conformance point that addresses, among other applications, the needs of the professional studio and post production environment. In the paper the requirements of such an environment for compressed digital video together with a functional description of the 4:2:2 Profile are given. The 422@ML provides a flexible compression solution that allows edit-ability, supports a wide range of bit rates, and provides good to excellent quality in both intra and inter studio environment. Our experiments show that the 422@ML is very robust in a multi generation environment, provides an efficient coding solution for transmission and storage, and provides transparency or near transparency in stressing operations such as digital video transformations, quality.