1 October 1998 Selection of transforms for better image compression
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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.
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Nitendra Rajput, Nitendra Rajput, R. K. Shevgaonkar, R. K. Shevgaonkar, } "Selection of transforms for better image compression", Proc. SPIE 3460, Applications of Digital Image Processing XXI, (1 October 1998); doi: 10.1117/12.323201; https://doi.org/10.1117/12.323201
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