[ Home  |  FAQ-Related Q&As  |  General Q&As  |  Answered Questions ]

    Search the Q&A Archives

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

<< Back to: comp.compression Frequently Asked Questions (part 1/3)

Question by siddhartha
Submitted on 12/26/2003
Related FAQ: comp.compression Frequently Asked Questions (part 1/3)
Rating: Not yet rated Rate this question: Vote
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
Rating: Not yet rated Rate this answer: Vote
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
Rating: Not yet rated Rate this answer: Vote
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

 

Your answer will be published for anyone to see and rate.  Your answer will not be displayed immediately.  If you'd like to get expert points and benefit from positive ratings, please create a new account or login into an existing account below.


Your name or nickname:
If you'd like to create a new account or access your existing account, put in your password here:
Your answer:

FAQS.ORG reserves the right to edit your answer as to improve its clarity.  By submitting your answer you authorize FAQS.ORG to publish your answer on the WWW without any restrictions. You agree to hold harmless and indemnify FAQS.ORG against any claims, costs, or damages resulting from publishing your answer.

 

FAQS.ORG makes no guarantees as to the accuracy of the posts. Each post is the personal opinion of the poster. These posts are not intended to substitute for medical, tax, legal, investment, accounting, or other professional advice. FAQS.ORG does not endorse any opinion or any product or service mentioned mentioned in these posts.

 

<< Back to: comp.compression Frequently Asked Questions (part 1/3)

[ Home  |  FAQ-Related Q&As  |  General Q&As  |  Answered Questions ]
© 2008 FAQS.ORG. All rights reserved.