FFT VS DCT

>
>I see that all are asking why DCT is better than FFT or DFT.
>Where FFT is prepered than DCT? Why ? Is it only for phase information?
>
>_____________________________________
>Do you know a company who employs DSP engineers?  
>Is it already listed at http://dsprelated.com/employers.php ?
>

DCT has a beauty of concentrating its energy to lower frequencies when
compared to high frequency energy concentration. Human eye are more
sensitive to low frequency than high frequency i.e. most of the
information is in low frequency components than high. So DCT is very ideal
tool to transform and to get maximum information out after quantisation.

  when you see frequency distribution of FFT then it's uniform all over
the N. so there is not much scope for quantisation and hence compression.

---
Deepak Sarwade

deepakect wrote:
>>I see that all are asking why DCT is better than FFT or DFT.
>>Where FFT is prepered than DCT? Why ? Is it only for phase information?

> DCT has a beauty of concentrating its energy to lower frequencies when
> compared to high frequency energy concentration. Human eye are more
> sensitive to low frequency than high frequency i.e. most of the
> information is in low frequency components than high. So DCT is very ideal
> tool to transform and to get maximum information out after quantisation.

FFT (DFT) has periodic boundary conditions, DST has the function go
to zero at the boundary, DCT has the derivative zero at the boundary.

-- glen