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Proceedings Paper

Selection of transforms for better image compression
Author(s): Nitendra Rajput; R. K. Shevgaonkar
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Paper Abstract

This paper investigates the compactness aspect of two transforms namely DCT and WHT. We define a parameter called Activity Index (AI) of the image which is the ratio of the first derivative energy in the edges and the total first derivative energy of the image. Sobel edge operator is used to obtain the edges in the image and the first derivative energy in these edges is computed. It is demonstrated that the activity index provides a good measure of the relative compression which the two transforms would give and therefore can help in choosing the transform for better compression of an image. Computations show that the WHT performs better for images having higher AI (close to 1) whereas if the AI is small (less than 0.5) the DCT's performance is superior. If AI is close to 0.5 both transforms give more or less same compression. The algorithm is tested on a variety of natural as well as robotic type of images.

Paper Details

Date Published: 1 October 1998
PDF: 10 pages
Proc. SPIE 3460, Applications of Digital Image Processing XXI, (1 October 1998); doi: 10.1117/12.323201
Show Author Affiliations
Nitendra Rajput, Indian Institute of Technology (India)
R. K. Shevgaonkar, Indian Institute of Technology (India)


Published in SPIE Proceedings Vol. 3460:
Applications of Digital Image Processing XXI
Andrew G. Tescher, Editor(s)

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