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Ramp from blue to transparent

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Jonnie Lewis
Ramp from blue to transparent
on Aug 7, 2011 at 9:51:11 pm


I'm struggling to understand where I'm going wrong with creating a ramp that goes from blue to transparent.

I have my video footage in one layer, and an adjustment layer above that.

I create a solid shape, apply ramp to it, and adjust the start colour to be blue, and the end colour to be black.

I then pre-compose the shape layer and place it above the adjustment layer which is above the video footage.

I turn on Luma Matte on the adjustment layer but the whole shape just disappears from sight.

Is there something that I'm not doing correctly?

Thanks in advance :)

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Greg Burrus
Re: Ramp from blue to transparent
on Aug 8, 2011 at 3:31:23 am

The issue you are having is that when you precomp your adjustment layer you are taking away what you want to adjust. This is assuming that you made sure move all attributes into the new comp when you made the precomp. What you would need to do to allow it still adjust whats below it is turn on collapse transformations. This however would not solve your problem because the blue will not give you full opacity.

What you can do is in your precomp make a solid and make a ramp from black to white. Then create a blue solid in your main comp and set that solid to luma matte and it will give you a gradient from blue to transparent. There are are other ways to do this with out precomping like using the brush tool set to paint alpha but this way seems the simplest to me and give you more flexibility overall I think.

Hope this helps and my explanation made sense.

Greg - Blog - Portfolio

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Roland R. Kahlenberg
Re: Ramp from blue to transparent
on Aug 8, 2011 at 3:38:00 am

The Luma Matte picks up luminance, sorta similar to brightness to create areas of transparency. If your blue is dark, then you'll get very little transparency after using it as a color within your track matte.

If all you want is a gradient, from blue to transparent, the apply the Lighten Blending Mode to the gradient layer.

Another option is to apply Shift Channels on the gradient layer and shift one of the RGB Channels into the Alpha Channel. In your case, the Blue will be an ideal choice.


Intensive AE & Mocha Training in Asia.

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Jonnie Lewis
Re: Ramp from blue to transparent
on Aug 10, 2011 at 11:37:32 am


Much appreciated.

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