Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

y DCT is extensive used in image compression?

Status
Not open for further replies.

naresh850

Full Member level 3
Joined
Jun 9, 2006
Messages
157
Helped
6
Reputation
12
Reaction score
4
Trophy points
1,298
Activity points
2,249
HI

could any one give me the brif discription about

y DCT is extensive used in image compression?

Regards,
NP
 

mondunno

Advanced Member level 4
Joined
Jan 11, 2007
Messages
119
Helped
15
Reputation
30
Reaction score
4
Trophy points
1,298
Activity points
1,907
hi naresh

image compression is basically to make use of human perception model. (where higher frequencies r not noticed)

dct helps u to represent the spatial signal as sum of spatial frequencies. using which you could quantize each spatial frequency by different quant level.

one important property is its one to one mapping(i.e. mainly the idct(dct(spatial signal)) = spatial signal and dct and idct dontleed to any loss )
 

naresh850

Full Member level 3
Joined
Jun 9, 2006
Messages
157
Helped
6
Reputation
12
Reaction score
4
Trophy points
1,298
Activity points
2,249
could u please explain in detail

Added after 0 seconds:

could u please explain in detail?
 

ramesh

Advanced Member level 1
Joined
Jan 19, 2003
Messages
424
Helped
14
Reputation
28
Reaction score
14
Trophy points
1,298
Activity points
2,943
In general all the transforms are orthoganal transforms. After applying the transform (1-D or 2-D) the energy is compacted into few samples. The DCT is the most optimum compared to other transforms in the sense of energy compaction. Since the energy distribution in the high frequency coefficients are neglible and hence can be discarded without significant loss in the image quality (exploiting the human psychovisual redundancy). Only the selected low frequency coefficients having significant energy distribution may be quantised and coded to reduce the bit rate for transmission or the size of the coded image for storage requiring less space.

Since the DCT is the real-part of the FFT, the computionally effiicient algorithm can implemented to realise the hardware.

Theoretically the most optimum transform is the K-L transform.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top