Track matte - how?!
 

Hi,
I have tried a track matte to allow a certain part of a still image to be transparent and allow the video footage behind to plan through it but I cant get it to work.
When I create the matte in photoshop does it have to be saved as a .psd or can I save as a more uniform format like .jpeg? Also should the video play through the black or the white area of the picture?
Any help would be much appreciated.

To use a track matte, you can make any black and white image work for you. from BMP to JPG to PSD.

Try this:

1. Create a track matte with a white background and a black circle in the middle.

2. Put clip one on track one and clip two on track two. Put the track matte on track three.

3. Apply the track matte key on to the clip on track two. Set the key to use Luma Matte instead of Alpha matte. Poke out the eyeball on track three to that the black and white image disappears.

You will see the clip from track two in the circle.

worked a treat! I tried so many things I cant believe I didnt stumble over that.
there is no problem in creating a track matte and having the video that is showing through also having a matte of its own (luma) applied to it is there?

There should be no problem, but get used to nesting sequences to make things a bit easier to keep track of.

grr now i've tried to do the same thing at work in the context that I actually need it to work and it hasnt.
I have a jpeg of a house on video 1. a .mov of a flame on video 2 and a matte on video 3 so that the sky around the house is black and everything else is white. The effect I want is for the flame to look like it is behind the house, licking up above its roof. I have applied the luma track matte to video 2 and played around with the matting so it says video 1 2 and 3. (3 worked for me at home)
however when i flick the eye next to video 3 I still see the flames infront of the house instead of showing in only the blacked area of the matte (i.e - the sky above the house)
what am I doing wrong?!

Are you forgetting to poke out the eyeball on the track matte track?

no i did that. its half working, u can see some of this flame however its only coming through in boxes, even tho the track matte itself is not made up of boxes. its very difficult to explain but I will keep trying with it.

ok I have worked out the problem but do not know how to solve it..
The flame footage (on video 2) that I am using is quite small so I used a scale keyframe to increase and position it. However this also seems to move the matte. Is there any way I can get this to rescale behind the matte, leaving it un-effected?
thanks

Drop the flame clip into a new sequence. Adjust the scale of the clip. Drop the new sequence onto track2 , and add the track matte filter.

that works brilliantly. It was because I hadn't created a new sequence with the flame clip as you suggested.
Many thanks for your help.