RE: Misc Codec Questions....

Hi Sebastien,

On Tue, 2002-05-21 at 16:43, Sebastien St-Laurent wrote:
> >> Hi.
> >>
> >> First of all, can someone confirm if the behavior i'm getting with
> >> the (2,2)
> >> wavelet is the same (i,e: No bit growth)?
> >
> >You can see this by looking on the equation for the lowpass
> >coefficient, it's simply a truncated (or rounded) weighted average of
> >the neighbor coefficient e.g. (x_i + x_{i+1})/2 for the (1,1) wavelet.
> >There is no bit growth.

There is no bit growth, ignoring normalisation constants, and ignoring
the fact that you introduce nonlinearity by rounding/truncating. You can
opt for bit growth if you need linearity. Don't forget your sqrt(2) and
sqrt(2)/2 normalisation factors.

> Which i guess is good since you don't need 16 bits to cary around so it's
> more memory efficient. I stil lhave to figure out why my SPHIT coder is
> doing so bad with this wavelet.

I would hazard a guess that perhaps you aren't taking the cumulative
normalisation factor into account when you are checking for
significance?

Keep well,
Ray
-- 
--
http://www.mythral.org/~ray/


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