Save image with foreground as alpha channel


I know the way to save an rendered image with the background as an alpha channel (RGBA + FBUF), this may be usefull to have a transparent background and allows to add a background in postprocessing with PS for instance. Is there a way to get the contrary ? I mean to keep only the background and the foreground as an alpha channel.

Thanks to all

by a simple click of buttons…not that i have ever heard of but try messing arround with the sequence editor. I’ve never tryed it before but you may get lucky.

Thx but I can’t figure how to use the sequence editor to get the expected result. Have you more information about the way to use it ?

With PS you shoud be able to negate the Alpha Channel.
Or use Paint Shop Pro. I`m shure there are many tools out there to acomplish it.

What I do is save the color picture, then I press “A” while in the render window, take a screen shot by pressing the “Print Screen” button, and then go into GIMP, load up the picture, “Paste as New”, cut out the alpha render in the render window, copy it, go back to your original color picture, then make a layer mask of the layer’s alpha, then paste it there. Apply the mask, and your done.

I am not sure what exactly you want to do here… do you want to put transparent holes in your background for some reason?

anyway, here are a couple ways that you can do this in the seq editor…

1)you could take the scene and use the zutilz plugin to mask out the forground (zutilz can mask by depth…the problem with this is the zbuffer is not antialiased so the edges will be jagged )

  1. make everything that you want masked out in the forground is a color that is not present in the background and use one of the chromakey plugins

a .blend file and a better explanation of what you want to do will probably give you even more replys and options…

Ok thanks guys I will experiment your proposals.