[FFmpeg-devel] [PATCH v2] avfilter/vf_edgedetect: properly implement double_threshold()

[lance.lmwang at gmail.com]

On Sat, Jul 04, 2020 at 01:03:48PM -0400, Andriy Gelman wrote:
> On Mon, 29. Jun 09:26, Valery Kot wrote:
> > On Sun, Jun 28, 2020 at 12:03 AM Andriy Gelman <andriy.gelman at gmail.com> wrote:
> > >
> > > lgtm. I saw a small improvement when testing.
> > >
> > > Would be nice to allow weak edges that become strong to trigger neighboring weak
> > > edges in the future.
> > 
> > Thanks for the comment.
> > 
> > You are right, ideally double_threshold should be recursive (seed from
> > each "high" peak and spread over "low" peaks). But then potentially we
> > may end up with width*height/2 recursion depth, which may lead to
> > stack overflow. So probably some recursion limit is needed, and hence
> > suboptimal solution.
> > 
> > Or iterative approach, running through the complete image again and
> > again checking if "low" peaks are touching already selected edge
> > pixels. Stop when no new pixels can be added to the edge. Better, but
> > still potentially width*height/2 iterations with width*height
> > operations each, completely killing performance.
> > 
> > Maybe later I'll try to implement it in a generic way, but this is out
> > of scope for this patch.
> > 
> > Regards,
> > 
> > Valery Kot
> 
> Any objections if I apply this patch? 

The patch look fine to me, but no sign-off?

> 
> -- 
> Andriy
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-- 
Thanks,
Limin Wang