Title: Facsimile-Based Video Compression [Abstract]
Author: Yi-Jen Chiu and Toby Berger
 

Title: Perceptual Considerations in Spatial-temporal Video Compression [Abstract]
Author:: Yi-Jen Chiu and Toby Berger
 

Title: Multiple Descriptions Encoding of Images [Abstract]
Author: P. Subrahmanya and Toby Berger
 

Title: Computer-based Video Telephone Over 28.8 kb Modem Link [Abstract]
Project Author: Jay Chunsup Yun
 

Title: Object Tracking with Dynamic User Override [Abstract]
Project Author:  Worawat Tangsangasaksri
 

Title: A Vector Quantized Design for Video Sequences Using a Deterministic Annealing Approach to Codebook Generation [Abstract]
Project Author:  Wayne G. Phoel
 

Title: Occlusion Detection and Edge Processing in a Correlation Based Object Tracker [Abstract]
Project Author:  Neilesh R. Patel
 

Title: Workstation/Modem Interfaces for Asynchronous Video Data Transfer [Abstract]
Project Author: Elya J.Kapelyan
 

Title: Facsimile-Based Video Compression
Author: Yi-Jen Chiu and Toby Berger
Published in: IEEE Transactions on Circuits and Systems for Video Technology

Abstract: We present a novel systematic scheme to compress videos via a breakthrough of perception-sensitive decomposition of video into a facsimile-map and an intensity vector. Capitalized on the insensitivity of human visual system to the mild change of pixel int ensity change in difference frame, we only have to update those pixel sites whose intensity changes are serious enough to cause visual discrepancy. This paper focuses on our modified schemes for facsimile-based encoding of the difference frames. The core of our approach is to combine zeroing of the weak pixel intensity differences in each difference frame with techniques analogous to those of the Group 3, Group 4 and JBIG facsimile standards to specify the locations of pixels that have high frame-to-frame intensity differences. Adjustment of the zeroing threshold permits trading off bit rate for picture quality. All these approaches are transform-free and pixel-based; some of them also involve no motion compensation and henc! e are completely free of block-bas ed artifacts and computationally economical. In the case of the motion-compensation-free approach, assuming provision has been made for A/D converted camera output to be pipelined into the computer CPU in real time, we envision a software-only realization of the compressor and decompressor for full color CIF formats at 30 frames per second on today's PowerMac and PentiumPC computers. Inspired by Shannon's source coding theorem, we extend facsimile-based video compression to coding by blocks in order to ac hieve enhanced tradeoffs between data rate and picture quality. We also present a hybrid method which combines 2-D block coding and run length coding.

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Title: Perceptual Considerations in Spatial-temporal Video Compression 
Author: Yi-Jen Chiu and Toby Berger
Published in: IEEE Transactions on Circuits and Systems for Video Technology

Abstract: Inspired by the classical psychological experiments which led to formulation of the Weber-Fechner law, we present our spatio-temporal compression techniques for perceptual coding of video. These schemes allow video codec systems to capitalize on limitations in the human visual system in order to appreciably improve the tradeoff between d ata rate, picture quality, computational complexity and latency. We discuss compression schemes that capitalize on perceptual redundancy to provide graceful degradation of video quality. When objects move fast in the video conferencing scene or when the network channel buffer is full, traditional compression algorithms temporarily provide lower-quality pictures by adjusting quantization factors in frequency domain in order to restrain the bitrate. Contrastingly, our algorithms cut the bitrate by compressing the spatio-temporal picture information in ways that are visually indistinguishable to human perception. For cases in which a still higher compression ratio is needed, we describe means for taking advantage of $masking$ effects to provide graceful degradation in video quality.

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Title: Multiple Descriptions Encoding of Images 
Author: P. Subrahmanya and Toby Berger 
Published in: DCT

Abstract: Consider the following multiterminal data compression problem. An image is to be compressed and transmitted to a destination over a set of unreliable links. If only one of the links is functional (i.e. data transmitted over all other links is completely lost), we would like to be able to reconstruct a low resolution version of our original image. If more links are functional, we would like the image quality to improve. Finally, with all links functioning, we desire a high resolution, possibly lossless reconstruction of the original image. This problem is related to the multiple descriptions problem in source coding literature. See [1] for a survey of the literature.

Several motivating applications exist for this problem. For instance, in a digital image archive, it is desirable to store low resolution versions of each image at multiple locations so that even if a few of them are unavailable/corrupted/destroyed, we can reconstruct approximations to the original image using those that survive. If all the low resolution versions are available, we would like to be able to reconstruct the original image losslessly.

Another example arises in the downloading of images from an image library over the internet. Traditionally, all images are stored at a single site in the network. If any part of the network route leading to a site is congested, viewers wishing to view an image on that site will be faced with debilitating delays. A solution to this problem is to place low resolution versions of the image at multiple sites. Even if some of the sites are congested, viewers can satisfy themselves with a lower resolution version of the image reconstructed using the sites that become available within a reasonable delay. If all the sites can be accessed, then the viewer would get a high resolution version of the image. Usually, lossy compression is used in this application in order to achieve the high compression ratios needed to use network bandwidth effectively.

We present conceptually simple and computationally efficient schemes that are useful in scenarios such as those described above. Our schemes can be implemented as simple pre-processing and post-processing operations on existing image compression algorithms.

Reference: V.Vaishampayan, Design of multiple description scalar quantizers, IEEE Transactions on Information Theory, IT-39(3):821-834, May 1993.

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Project Title: Computer-based Video Telephone Over 28.8 kb Modem Link  
Author: Jay Chunsup Yun

Abstract: Over the past few years, several M.Eng projects concentrated on developing techniques for a video telephone system that runs on a computer and communicates over a regular telephone line. These project yielded encoder and decoder software with some performance limitations. While the decoder is able to provide real-time decoding at 10 to 15 frames per second, the encoder runs too slow for a realistic application. This continuation project focuses on enhancing the execution time of the encoder software and on preparing for full-duplex operation.

The project has three main objectives:

1. Improving the encoder algorithms for faster and simpler executions.
2. Combining the encoder and the decoder into a single application.
3. As time allows, designing techniques for problems not yet dealt with.

The frame rate of the resulting encoder algorithm is increased by over three times. Complete, full-duplex operation is not achieved in this project, but the video telephone software is able to encode and decode concurrently. The project leaves many detailed suggestions for future development.

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Project Title: Object Tracking with Dynamic User Override
Author: Worawat Tangsangasaksri

Abstract: A program was developed to demonstrate the performance of object tracking in the motion compensated video codec. The video compression program is based on the software modules developed by members of the DISCOVER lab; the modules werecombined with a display function to show the result of the decoded image frame by frame as in real-time processing. A mouse-driven user interface was developed to provide a convenient means for initializing the object tracker box andenabling the user to reset the box location when the object tracking algorithmfails. An enhanced algorithm for motion estimation that improves the processing speed with negligible quality degradation is introduced.

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Project Title: A Vector Quantized Design for Video Sequences Using a Deterministic Annealing Approach to Codebook Generation
Author: Wayne G. Phoel

Abstract: This project employs deterministic annealing to determine the codebook for encoding difference frames of head images isolated from a video sequence. The purpose of this project is to attempt to encode image sequences in a manner that will meet the existing need for high quality inter-office video conversation.

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Project Title: Occlusion Detection and Edge Processing in a Correlation Based Object Tracker 
Author: Neilesh R. Patel 

Abstract: A robust object tracker has been developed for use in video conferencing codecs. This tracker operates on the principle of hierarchical block matching. Objects are able to be tracked as they translate, moderately rotate, or slightly deform.

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Project Title: Workstation/Modem Interfaces for Asynchronous Video Data Transfer
Author: Elya J.Kapelyan

Abstract: This project deals with issues related to the design and implementation of terminal software for high-speed (28.8 Kbps) transfer of compressed video frames over telephone line. In particular, methods of parallelizing time-critical routines within the UNIX operating system are discussed.

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