[FFmpeg-devel] [PATCH 2/2] libavfilter/vf_colorconstancy.c : Adding weighted greyedge

[Yatendra Singh]

>
> > +    s->difford = 1;
>
> Why are you forcing this value?
>
The algorithm only uses first order differentials for the calculation of
the specular variant and it does not seem to be an option to use other
orders as far as I have understood from the paper and the official code.

>
> If you are setting initial estimation to normal white, does it make any
> difference to do a chromatic adaptation?
>
 I was trying to reproduce the same values as the official code in matlab
and hence this was done.
 It might provide a very minor improvement in speed but having an estimate
beforehand might help converge faster.
 I would update the next patch with chromatic adaptation.

>
> > +
> > +static const AVOption weighted_greyedge_options[] = {
> > +    { "minknorm",  "set Minkowski norm",         OFFSET(minknorm),
> AV_OPT_TYPE_INT,    {.i64=1},   0,    20,     FLAGS },
> > +    { "sigma",     "set sigma",                  OFFSET(sigma),
>  AV_OPT_TYPE_DOUBLE, {.dbl=1},   0.0,  1024.0, FLAGS },
> > +    { "min_err",   "set minimum angular error",  OFFSET(min_err),
>  AV_OPT_TYPE_DOUBLE, {.dbl=0.1}, 0.02, M_PI,   FLAGS },
> > +    { "max_iters", "set the maximum iterations", OFFSET(max_iters),
> AV_OPT_TYPE_INT,    {.i64=10},  1,    100,    FLAGS },
> > +    { "kappa",     "set the kappa for weights",  OFFSET(kappa),
>  AV_OPT_TYPE_INT,    {.i64=10},  1,    25,    FLAGS },
>
> Why 25?
>
 Honestly, I have no idea as to what the actual upper limit on the power of
weights should be, so I used a random upper limit while testing.
 What would you suggest I should use?


I would also update the new patch with all the rest of the changes.