Re: rephase my problem: how to reduce round-off error for hardware implementation?

> The very un-scientific method. "Trial and error". )-: What is known,
however,
> is that the statistics of wavelet high-passes is typically a "long tail
> symmetric" function centered around the origin. This naturally asks for a
> reconstruction point set off towards zero. There are even some model-
> distributions that would allow you to compute *where exactly* the
reconstruction
> point would have to be. The reason why we choose 3/8th and not the precise
> minimum was very simple: The 3/8th solution is quite easy to implement in
> fix point. (*3, shift right three bits).
>


Dear Prof. Thomas,

Thanks a lot for your answer!

I still am not quite sure about your mechanism about the 3/8th bin? Can you
give me some more detailed explanations on how you do that?

For normal JPEG decoding, it is quite simple: just let's say we have
quantized and rounded coefficients Y, which is a 8x8 matrix...

We just need to element-wise multiply it with Q matrix, then take IDCT...

So X=IDCT2(Y.*Q)

That's all, very simple! But now with your 3/8th scheme, do we do

X=IDCT2((Y-3/8).*Q)   ???

I know this is come from Laplacian assumption of DCT coefficients... but I
just don't know how to do it in practice...

Thanks a lto,

-Walala