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View Full Version : Image sequence as mask/selection?


craiggulow
02-14-2008, 10:55 AM
I'm giving the trial version a play. I'm wondering if you can use an image sequence as a mask for an operator. I haven't found anything in the help file (which I easily could have missed as I've barely "kicked the tires" on this thing), but if it's possible to do this I'd appriciate it if someone could point me at the relevant material in the manual.

TIA

scrimski
02-14-2008, 11:02 AM
Search for "matte" or "stencil" or "cut out".

craiggulow
02-14-2008, 11:36 AM
Thanks Scrimski, but those features don't provide the functionality I'm looking for. It's pretty simple, I have Image Sequence A and Image Sequence B. Image Sequence B is greyscale. I want to apply an operator (a blur, a sharpen, whatever) to Image Sequence A, but using Image Sequence B as the selection for the operator.

I'm wondering if to do this, you'd have to apply the operator to the footage and save it out. Then comp it using Image Sequence B as a matte onto the original sequence?.

scrimski
02-14-2008, 11:49 AM
Take A as input for B, which will create C, blur/sharpen/whatever C, put C on top o A.

PiXeL_MoNKeY
02-14-2008, 05:37 PM
1) Apply Selections > Compound Channel Selection to Image A
2) Set Image B as the Layer, Use Red, Blue, or Green (Since Greyscale will be equal values)
3) Apply operators that you want applied to the greyscale area
4) Add a remove selection operator to disable the selection in the flow (this disables the selection so any operators added after that will apply to the whole image).

Note: The selection values will be black = 0%, white = 100%, grey somewhere in between.

-Eric

craiggulow
02-14-2008, 07:23 PM
Thanks Eric. I was hoping that it was a smoother process (more of a "image sequence selection" operator), but I guess not enough people are creating custom masks in 3D (?). Figured that would a fairly common practice.
Anyway, thanks again.

PiXeL_MoNKeY
02-15-2008, 01:43 AM
The compound channel selection is the "image sequence selection" operator. It uses the value (R, G, B, or A) as a selection. It also, has options for Replace, Add, Subtract, or Intersect the existing selection. So it is a very powerful tool that can create various selections based on an input channel value.

But you have to also remember that combustion is like the modifier stack in Max. If you enable selection, but don't turn it off then that selection is applied to everything on top. The Remove selection operator just turns off the selection for anything added on top of it.

-Eric

craiggulow
02-15-2008, 02:03 AM
Ha! When I was following your directions I was thinking, "Hey, this is just like the max modifier stack." Has it always worked this way in Combustion? I never really payed too much attention to it (except for that Speed (the movie) bus demo they showed us at some siggraph ages and ages ago).

PiXeL_MoNKeY
02-15-2008, 03:33 AM
As far as I know it has abeen like that. I have owned and used it since version 2.

-Eric

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