[Bf-cycles] Sample filtering options

[Mohamed Sakr]

I will add the Blackman-Harris soon once I have a free 2 days.

On Thu, Aug 6, 2015 at 6:33 PM, Brecht Van Lommel <
brechtvanlommel at pandora.be> wrote:

> I strongly suggest to not add any pixel filters with negative weights
> to Cycles, like Catmull-rom, Sincor Lanczos. In my opinion they only
> add problems and I would not suggest anyone to use them in practice.
> Blackman–Harris could be good to add, since that's a filter with
> positive weights that supposedly has less ringing than Gaussian. But
> it's the only one I can think of.
>
> With a path tracer like Cycles there's enough AA samples that you
> don't need to artificially sharpen the image, and deal with problems
> like ringing or clamping negative values. I think it's a legacy
> feature that is no longer needed. The large filter collections offered
> by renderers was never useful in my opinion, it's just needless UI
> complexity, most of the filters are just not good.
>
> Also note that denoising algorithms work best with filter importance
> sampling since all the pixels are then decorrelated. So if a denoiser
> is implemented at some point it would be simplest if it just worked
> with all filters.
>
>
> On Thu, Aug 6, 2015 at 5:12 PM, Nathan Vegdahl <cessen at cessen.com> wrote:
> > Yes, I am talking about pixel/sample/AA filters.  Look up the paper
> "Filter
> > Importance Sampling" for more information.
> >
> > As for texture filtering, I'm sure there's more flexibility there, as I'm
> > pretty sure it uses more standard techniques.
> >
> > --Nathan
> >
> > On Aug 6, 2015 8:08 AM, "Yury Baranov" <cucumberer at gmail.com> wrote:
> >>
> >> Hi,
> >> I was talking about other filters (maybe they called AA filters). There
> >> are two of them ATM: Box and Gaussian. And Bitmap filters are Smart,
> Cubic,
> >> Closest and Linear.
> >>
> >> 2015-08-06 18:01 GMT+03:00 Nathan Vegdahl <cessen at cessen.com>:
> >>>
> >>> IIRC Cycles uses "filter importance sampling" to do its sample
> filtering.
> >>> This has some advantages, but one of its disadvantages is that it
> doesn't
> >>> work well with filters that have negative lobes (the resulting renders
> are
> >>> very noisy).
> >>>
> >>> All the filters you mention have negative lobes, so although they
> >>> technically could be implemented, my guess is that they won't be.  It
> would
> >>> be very unexpected behavior to a user if they switched filters and
> suddenly
> >>> their image was twice as noisey.
> >>>
> >>> --Nathan
> >>>
> >>> On Aug 6, 2015 7:38 AM, "Yury Baranov" <cucumberer at gmail.com> wrote:
> >>>>
> >>>> Hi. Is it planned to make more sample filtering options like
> >>>> catmull-rom, sinc, lanczos etc.? Maybe more filtering options for
> bitmaps
> >>>> will be good, too.
> >>>>
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> >>
> >>
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