Video Compression Using Wavelets.

Date of Submission

December 2002

Date of Award

Winter 12-12-2003

Institute Name (Publisher)

Indian Statistical Institute

Document Type

Master's Dissertation

Degree Name

Master of Technology

Subject Name

Computer Science


Machine Intelligence Unit (MIU-Kolkata)


Murthy, C. A. (MIU-Kolkata; ISI)

Abstract (Summary of the Work)

A video stream consists of a series of still images or frames displayel in rapid succession. Transmitting video over a network can be expensive in terms of bandwidth utilization. When more bandwidth is consumed by video, less is available for other applications such as voice, data and mission critical systems. In addition to this, over wide arca networks where usage charges may apply, transmitting large video streams can become cost prohilbitive. Limited storage online has fed the need to compact this information into the smallest size possible. The development of compression programs such as “zip”have sufficiently met this need for data, but leave streaming media such as video and audio untouched. As the trend to display video on the desktop grows, it is vital that this data gets compressed. Digital video could only be used in wider applications if the storage and bandwidth requirements could be eased; easing these requirements is the purpose of compression. In this project two specifie compression techniques for video frames are addressed.1.2 Applications of Video CompressionVideo compression is used in many applications to reduce the amount of information required to represent a sequence of frames. There is a tremendous variety of applications for video compression. Some of them are’Video Conferencing, Video phone, Video mail, Video games, Video Library, Broadcasting, Video-on-demand, Cable TV distribution.1.3 Relevant methodologyVideo Compression techniques are becoming increasingly important due to present and forth- coming visual services and applications on the internet. This ever-expauding area has generated a lot of research and increased standardization activities.Some of the methods available on video compression are as follows.• An elementary approach [1]An elementary approach to video compression would be to employ any of the still image compression techniques on a frame by frame basis. However, the compression that can be achieved by such an approach will be limited because each frame is treated as an independent image.The methods which are later developed are interframe compression methods which exploit the temporal redundancies, due to similarity between neighbouring frames, to provide superior compression efficiency.• Subsampling [2]The encoder selects every alternate frame and writes it on the compressed stream. This yields a compression factor of 2. The decoder inputs a frame and duplicates it to create two frames.• Differencing [2]A frame is compared to its predecessor. If the difference between them is small, the encoder encodes the pixels that are different by writing three numbers on the compressed stream for each pixel : its image coordinates, and the difference between the values of the pixel in the two frames. If the difference between the frames is large, the current frame is written on the output in the raw format.A lossy version of differencing looks at the amount of change in the pixel. If the difference between the intensities of a pixel in the preceding frame and in the current frame is smaller than a certain threshold the pixel is not considered different.


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Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


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