[XviD-devel] Hadamard Transform

[Christoph Lampert]

On Thu, 5 Sep 2002, Marc FD wrote:

> > a'  =  (a + b + c + d + e + f + g + h) /8
> > b'  =  (a + b + c + d - e - f - g - h) /8
> > c'  =  (a + b - c - d - e - f + g + h) /8
> > d'  =  (a + b - c - d + e + f - g - h) /8
> > e'  =  (a - b - c + d + e - f + g - h) /8
> > f'  =  (a - b - c + d - e + f + g - h) /8
> > g'  =  (a - b + c - d - e + f - g + h) /8
> > h'  =  (a - b + c - d + e - f + g - h) /8
> 
> ARGH !!!!! this is FALSE !! i've lost 2 hours on it =(

Ooops, you're right... It should be  4 plus and 4 minuses in
every column. I wish there were drag-and-drop for formulas...

Sorry :=( 

gruel

P.S. I thought you used the butterfly? Then result will come
out right, no matter how stupid my typos would have been. 8-}

P.P.S. If you do this in 16bit, you can forget about the 
'/8' for our purposes. We don't care about a constant in 
front of everything... In 8bit of course you can't.