<div dir="ltr">I did a quick B-H implementation based on Lux's code a while back. I'll post here if I can find the file.</div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Aug 6, 2015 at 1:06 PM, Mohamed Sakr <span dir="ltr"><<a href="mailto:3dsakr@gmail.com" target="_blank">3dsakr@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">I will add the Blackman-Harris soon once I have a free 2 days.</div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Aug 6, 2015 at 6:33 PM, Brecht Van Lommel <span dir="ltr"><<a href="mailto:brechtvanlommel@pandora.be" target="_blank">brechtvanlommel@pandora.be</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I strongly suggest to not add any pixel filters with negative weights<br>
to Cycles, like Catmull-rom, Sincor Lanczos. In my opinion they only<br>
add problems and I would not suggest anyone to use them in practice.<br>
Blackman–Harris could be good to add, since that's a filter with<br>
positive weights that supposedly has less ringing than Gaussian. But<br>
it's the only one I can think of.<br>
<br>
With a path tracer like Cycles there's enough AA samples that you<br>
don't need to artificially sharpen the image, and deal with problems<br>
like ringing or clamping negative values. I think it's a legacy<br>
feature that is no longer needed. The large filter collections offered<br>
by renderers was never useful in my opinion, it's just needless UI<br>
complexity, most of the filters are just not good.<br>
<br>
Also note that denoising algorithms work best with filter importance<br>
sampling since all the pixels are then decorrelated. So if a denoiser<br>
is implemented at some point it would be simplest if it just worked<br>
with all filters.<br>
<div><div><br>
<br>
On Thu, Aug 6, 2015 at 5:12 PM, Nathan Vegdahl <<a href="mailto:cessen@cessen.com" target="_blank">cessen@cessen.com</a>> wrote:<br>
> Yes, I am talking about pixel/sample/AA filters. Look up the paper "Filter<br>
> Importance Sampling" for more information.<br>
><br>
> As for texture filtering, I'm sure there's more flexibility there, as I'm<br>
> pretty sure it uses more standard techniques.<br>
><br>
> --Nathan<br>
><br>
> On Aug 6, 2015 8:08 AM, "Yury Baranov" <<a href="mailto:cucumberer@gmail.com" target="_blank">cucumberer@gmail.com</a>> wrote:<br>
>><br>
>> Hi,<br>
>> I was talking about other filters (maybe they called AA filters). There<br>
>> are two of them ATM: Box and Gaussian. And Bitmap filters are Smart, Cubic,<br>
>> Closest and Linear.<br>
>><br>
>> 2015-08-06 18:01 GMT+03:00 Nathan Vegdahl <<a href="mailto:cessen@cessen.com" target="_blank">cessen@cessen.com</a>>:<br>
>>><br>
>>> IIRC Cycles uses "filter importance sampling" to do its sample filtering.<br>
>>> This has some advantages, but one of its disadvantages is that it doesn't<br>
>>> work well with filters that have negative lobes (the resulting renders are<br>
>>> very noisy).<br>
>>><br>
>>> All the filters you mention have negative lobes, so although they<br>
>>> technically could be implemented, my guess is that they won't be. It would<br>
>>> be very unexpected behavior to a user if they switched filters and suddenly<br>
>>> their image was twice as noisey.<br>
>>><br>
>>> --Nathan<br>
>>><br>
>>> On Aug 6, 2015 7:38 AM, "Yury Baranov" <<a href="mailto:cucumberer@gmail.com" target="_blank">cucumberer@gmail.com</a>> wrote:<br>
>>>><br>
>>>> Hi. Is it planned to make more sample filtering options like<br>
>>>> catmull-rom, sinc, lanczos etc.? Maybe more filtering options for bitmaps<br>
>>>> will be good, too.<br>
>>>><br>
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>>><br>
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>><br>
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