After Effects fringing even after properly interpreting footage

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  01 January 2013
Smile After Effects fringing even after properly interpreting footage

Hi everyone.

I have rendered a sequence in Softimage with straight alpha. The image sequence is outputted in Gamma 1.0 and is an open exr. In AE project settings I have set the color settings to 32 bpc and checked the Linearize Working Space. In the interpret footage window I have set it to straight alpha and in the Color Management tab I have set the profile to Preserve RGB.

Still I am getting white fringe. Fought the whole day but couldn't fix it. I am very new to AE. Please help.

Hi I have noticed that the white fringe appears only when I re scale or rotate the footage. In it's default size it looks fine, with no fringing whatsoever.


P.S - Sorry but I might have accidentally triple posted the same thread. The first two post I posted from IE and Firefox, weren't showing up. So I used Chrome the third time and it seemed to work. Sorry again.

Last edited by BubbaDaCaveman : 01 January 2013 at 08:22 AM. Reason: Added more information
  01 January 2013
Try interpreting 'Premultiplied - Matted With Color' and set it to white(or whatevr color your fringe is)
  01 January 2013
Hi. I tried that earlier and that didn't work

I have edited the first post to add the following information.

Fringing occurs only when I Scale or Rotate the object.

Also if I change the Color Settings Depth from 32 bpc to anything lower the fringing goes away but the colors from the flame goes away too and the flame turns to grayscale.

Attached an open exr from the render. Please check.
Attached Files
File Type: zip (192.5 KB, 5 views)

Last edited by BubbaDaCaveman : 01 January 2013 at 08:35 AM.
  01 January 2013
wow, that's interesting because I get a black fringe.
  01 January 2013
Where does that render come from(which program, which renderer?)
  01 January 2013
Probably you are aren't using any Color Management. I get black fringe too when I do not use color management.

It is rendered in Softimage 2013 Mental Ray. The flame has a very high HDR value to it.
  01 January 2013
It's because you have negative values in your alpha along the edge of the object. You need to clamp them to 0. Apply a Channels -> Minimax to your layer, set it to Minimum 0 and make sure it's set to effect the alpha only.
  01 January 2013
Hi using any 16 bit plugin removes the color from the flame. The Minimax plug-in being 16 bit, turns the flame black and white.

The fringe appears only when I re scale or rotate the footage. I have tried all the plugins from the Matte category and none of them works so far.

How did you find out that the Alpha has negative values

Dropping the Quality to Draft also removes the fringe

Last edited by BubbaDaCaveman : 01 January 2013 at 07:05 AM.
  01 January 2013
OK, actually they're not negative values, but they are showing up as invalid - NaN pixels (Not a Number).

If you draw a horizontal line across the top of the flame and the bottom of the bowl, within that rectangle, over the black background is where these values are. I don't know if there is some material that rendered in the background or what, but something is in your 3D scene I think that is creating these NaN pixels.

Also, I don't think 16bit filter is what is causing the flame to appear B&W, I think it's just the way the alpha of the flame is made, it has a very low value in the flame area, so most of it dissappears when you multiply it with the alpha.

Last edited by theta2 : 01 January 2013 at 06:31 PM.
  02 February 2013
I think AE has a problem with the Straight Alphas' in my renders. Not only this but older renders with Straight Alpha has this problem too. I re rendered a flame frame with Premultipled Alpha and checked that in AE, annd there was no fringing even if I scale or rotate it. No NaN either.

These images composited without a problem in Nuke and Softimage's inbuilt compositor.
  02 February 2013
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