Adobe Photoshop Forum
Parent Child Compositing
Parent Child Compositing
by Joost on Apr 19, 2005 at 9:35:27 am

This may be a silly question for some of you experts, but OK, I will ask it anyway...

For video editing I work with Sony Vegas, and I love the parent-child compositing technique. I want to do something similar with still images in Photoshop. I see all the possibilities with layers in Photoshop, but I can't find a way to make a parent-child composite. Can anyone shed some light into my darkness?

For those who are not familiar with the term: in parent-child compositing two images (A and B) are mixed by way of a third image (C), which is a greyscale image. A white pixel in C means image A is visible, a black pixel in C means image B is visible. A grey pixel in C determines a mix of image A and B. This is in essense what I want with my stills.

Any help is very welcome. Thanks.


Re: Parent Child Compositing
by Kim Mackenzie on Apr 19, 2005 at 1:42:02 pm

This is the only way coming to mind - basically, use a positive of your Layer C as a mask on one layer, and a negative of it as a mask on the other.

Re: Parent Child Compositing
by Filip Vandueren on Apr 20, 2005 at 10:30:50 am

Hi Kim,

If both layers were fully opaque to start with, there's no need to do it for the bottom layer too.
Because at a input value of 50% grey,
both layers would be at 50 % opacity, wich does not add up to 100%

And here's a faster way;

If that's wrong, you should invert the mask.

Re: Parent Child Compositing
by Kim Mackenzie on Apr 20, 2005 at 12:27:36 pm

Oh duh :) Yer right, of course.

Re: Parent Child Compositing
by Tim Neighbors on Jul 9, 2015 at 1:45:30 am

I realize this is a very old post, but thought I'd share... select a layer in photoshop and press control+alt+G (on a PC). This will make it a child of the layer below. Make that child layer a multiply layer and put your mask in it with one of the images the parent (directly below), and the other below that. ...just another way to accomplish the same thing.