View Full Version : How to use alpha channels in photoshop??

06 June 2003, 04:24 AM
Hi all

I know this is very basic stuff but i've not done this before.

I'm using Maya 4.5 and I'm trying now to get to grips with rendering in passes and layers and the first step for me was to set up a simple scene....a sphere on a plane and render out a background layer, sphere layer and shadow layer....

I have the alpha channels intact but when I bring them into photoshop I'm not sure how to order the layers correctly or what mode to use to get the alpha channel to do it's thing!!

Anyone point me in the right direction?


06 June 2003, 04:29 AM
Well I'm assuming that you plan to composite a still iamge in Photshop rather than in after effects or some other compositng program.. this would not be such an issue in that case.

So what you want to do is to laod selection and invert in under selections and then delete the background to a transparent color.

Then you can paste the reflectiive layer an duyse a additive tranfer mode and use tranparency to control the intensity etc.

06 June 2003, 05:02 AM
mmmm....I had assumed that the process would be the same for still image or movie sequence.....I was testing some methods in photoshop first.....

I'm actually planning to use premiere to composit a movie sequence (I know not the best comp app but all I have access to) what's the process for that?



06 June 2003, 10:08 AM
Premeire isn't really a compositing app. It's more for video editing. But if you want to composite in Photoshop you can ctrl+click the alpha thumbnail to make it a selection and then copy and paste the rgb layer. In After Effects there is a checkbox for alpha masks as well so if you import a tif sequence it'll automatically mask the frames and you can layer in AE.

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