Black outline pixels on my render output images

[prestyprasad]

Hai .i have a problem during vray render.i got the output but image is with black pixels on some objects .why it is like that .how to resolve it .pls help

[Chris MacDonald]

It's because:

 

1) you're using a sharpening filter - this is what causes the black ringing and...

 

2) the (floating point) contrast between light/dark is too great for the antialiasing sampler to resolve.

 

Your options are one of or a combination of:

 

A) Render at higher resolution. The problem will still be there, but will effectively be reduced in size.

B) Use a softer AA filter (sharp filters look shit anyway)

C) Clamp the output to something low enough for the AA filter to deal with.

D) Turn on sub-pixel mapping - Generally clears up the issue, but at a cost of image quality (depends if you notice it or not).

E) Use max ray intensity (may/may not work) - akin to clamping output, but not quite.

F) Use lens effects (glare/bloom) to hide the issue.

 

I've highlighted what I'd do, personally.

Edited March 16, 2018 by Macker

[prestyprasad]

I use catmull rom filter

[Chris MacDonald]

Why do you use catmull rom? Because a tutorial told you to?