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why do we do transorms like DCT,DWT etc.Can we compress an...

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Question by siddhartha
Submitted on 12/26/2003
Related FAQ: comp.compression Frequently Asked Questions (part 1/3)
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why do we do transorms like DCT,DWT etc.Can we compress an image
without applying these transforms?
Please explain with more practical reasoning.


Answer by Maelstrom
Submitted on 3/9/2005
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These transforms allow you to change the data into a format where you can alter the information without changing the picture significantly, and where such alterations make it so that the image data is more compressible.

 

Answer by Ashok kumar.
Submitted on 7/11/2007
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Transmission and storage of uncompressed video would be extremely costly and  impractical
The wavelet transform (WT) has gained widespread acceptance in signal processing and image compression.
Because of their inherent multi-resolution nature, wavelet-coding schemes are especially suitable for applications where scalability and tolerable degradation are important.
Advantages of DWT over DCT
No need to divide the input coding into non-overlapping 2-D blocks, it has higher compression ratios avoid blocking artifacts.
Allows good localization both in time and spatial frequency domain.
Transformation of the whole image„³ introduces inherent scaling
Better identification of which data  is relevant to human perception„³ higher compression ratio
and many more reason why DWT we use in the image compression.
i hope u grasp something from this...thank you.. have a nice day

 

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