Warp wrote:
>  The problem is exactly the same as with antialiasing: Preclipping
> will always produce nice and smooth results (which is what people
> usually want) but subpixel-sized brighter-than-1 details will be more
> or less lost. Postclipping behaves in the exact opposite way:
> Subpixel-sized details will show up, but brighter-than-1 pixels
> will have ugly aliasing artifacts.
>  The former works ok in 99.9% of cases but is still not perfect.

I don't think it's the job of antialiasing to make tiny subpixel bright 
stars and the like show up. This is the job of some kind of glare filter 
(which however doesn't exist in official POV-Ray, but that's another issue) 
that is applied before AA. This is why I find pre-clipping for AA to be 
correct.

Focal blur on the other hand should be applied before clipping, since focal 
blur, just like glare effects, should be able to make small ultra-bright 
spots become large still-rather-bright spots. The problem with artifacts 
seem to me to only occur because AA (with clipping after the focal blur but 
before the AA) is disabled when focal blur is enabled. I see no reason why 
both can't be enabled at the same time.

Wouldn't the problem in Jaime's specific case here be solved if AA and 
traditional focal blur (that is, no pre-clipping) could be enabled at the 
same time? I'm not sure, but it sounds likely to me at least.

Rune
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