Re: [9fans] image/memimage speed

["Iruata Souza" <iru.muzgo@gmail.com>]

On Sun, Nov 30, 2008 at 8:00 PM, Iruata Souza <iru.muzgo@gmail.com> wrote:
> 9fans,
>
> I'm playing with nearest-neighbor image resampling and wrote two
> simple implementations - http://tmp.oitobits.net/iru/nn.c,
> http://tmp.oitobits.net/iru/nnmem.c - one using draw(2) and the other
> using memdraw(2).
>
> running them on the same image on disk shows that nnmem is way faster:
>
> cpu% nnmem acme.wd
> spent 0.127344 seconds on resampling
> cpu% nn acme.wd
> spent 6.111893 seconds on resampling
>
> looking at the code you see nn.c calls unloadimage() to fill oscan
> with the data from m; oscan is then used for the interpolation. that
> pass is not needed in nnmem.c because of byteaddr() gives us the
> address of the first byte of data in m, the memimage in question.
>
> what I'm seeking is a way to avoid the unloadimage() call in nn.c, if
> that's possible - which, by my understanding of the manual and code,
> is not.
> alternatively I could try drawing the memimage to the screen, which I
> did not find possible directly, only by converting it to an image.
> any ideas?
>
> sorry if I'm missing the obvious.
>

mostly everything here is now understood by me. sorry for the noise.

iru