• Adobe Photoshop

  Parent Child Compositing

  Posted by Joost on April 19, 2005 at 9:35 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.

  Joost

  Tim Neighbors replied 10 years, 10 months ago 4 Members · 4 Replies
• 4 Replies

• 

  Kim Mackenzie

  April 19, 2005 at 1:42 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.
• 

  Filip Vandueren

  April 20, 2005 at 10:30 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;

  • Get the three layers situated in your file
  • make only layer C visible
  • switch to channels and command-click on the RGB-channel -> turns the grayscale equivalent into a selection
  • hide layer C, show layer A & B
  • Select layer B (you should still sea the ‘marchin ants’ of your complex selection.
  • click on the layer-mask icon -> it automatically creates a layer mask that’s equal to the current selection

  If that’s wrong, you should invert the mask.
• 

  Kim Mackenzie

  April 20, 2005 at 12:27 pm

  Oh duh 🙂 Yer right, of course.
• 

  Tim Neighbors

  July 9, 2015 at 1:45 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.

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