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

[Andriy Gelman]

On Sun, 05. Jul 09:37, lance.lmwang at gmail.com wrote:
> 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?
> 

Thanks, will add one.

-- 
Andriy