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Activity Forums Adobe After Effects How can I get the black in Fractal Noise Effect to be transparent?

  • How can I get the black in Fractal Noise Effect to be transparent?

    Posted by Jesse Skellington on June 22, 2007 at 8:44 am

    Hi all,

    I am trying to use the Fractal Noise Effect to make a cloud animation to be edited in Photoshop for video game sprites. This means I need the black part of the Fractal Noise to be transparent. I thought if I saved it as a “TARGA sequence” Format and set the channels to RGB+ALPHA. Then I could just load the ALPHA and delete the black but I am not getting the ALPHA in the channels. I know I am missing some thing here but what could it be?

    Big Thanks

    Graham Quince replied 2 years, 6 months ago 6 Members · 6 Replies
  • 6 Replies
  • Jonathan Pitzer

    June 22, 2007 at 12:44 pm

    A very easy to accomplish this is to play with the blending modes on the layer. You can do this by selelcting the layer and clicking “ctrl +” or “ctrl -“. Another thing that you might try is doing a luma key and key out darker.

  • Kevin Camp

    June 22, 2007 at 1:19 pm

    you could create your alpha in photoshop by copying the image and pasting it in the alpha channel. since it is a sequence, you could create and action to do this, and use that to create batch process.

    you could do a similar process in after effects, using the fractal noise as a track matte and re render the sequence, making sure the render settings are set to render, rgb+alpha, millions+ and straight-unmatted. if you want some of the fractal noise detail to act as shading also, duplicate the noise layer, and for the lower layer, choose luma matte from the track matte pulldown. if you just want the ‘fill’ as a solid color, with only the alpha creating the detail, add a solid (pick your color, maybe white), move that below your noise layer then choose luma matte as the track matte for you solid layer.

    or the easiest way, find an effect called unmult (free), download and install it. when you apply the effect, it will key the black areas out. then render with the alpha settings mentioned above.

    Kevin Camp
    Designer – KCPQ, KMYQ & KRCW

  • Kevin Camp

    June 22, 2007 at 1:22 pm

    one note: if you use the unmult effect, i think you will need to pre-comp your fractal noise layer and apply unmult to the pre-comp.

    Kevin Camp
    Designer – KCPQ, KMYQ & KRCW

  • Sergio Aguero

    January 13, 2022 at 7:31 pm

    I know this is far too late, but whoever stumbles on this google search option again, I solved this with luma key. This plus a combination of a track matte really allowed to control where I wanted my fractal noise to be.

  • Scott Thomas

    January 13, 2022 at 9:23 pm

    Also, you can use Set Channels and Curves.

    Set Channels: “Set Alpha to layer’s Luminance”

    then add a curve and adjust only the Alpha.

  • Graham Quince

    January 16, 2022 at 12:21 pm

    There’s also the Extract effect in Keying, which will allow you to cut out the black elements, but to be honest – all the above suggestions work too!

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