It's not clear from your description what you're doing -- but here's how you use the Difference Matte effect.
Apply the effect to a clip on your timeline.
Right-click on this clip and select Show Properties to open the Properties panel.
In the Properties panel, find and open (if necessary) the Difference Matte listing. To the right of it's listing, next to the stopwatch, is a little icon. (Hover over it and it will show "Setup".)
Click on this icon and a browse screen will open. Browse to the photo you'd like to use as the Matte source for the effect.
You can then adjust the difference level as needed.
Do you have one of my books (available on Amazon.com or the Muvipix store)? They offer great descriptions and step-by-step instructions for nearly all of the program's tools.
Thanks for your response.
I have indeed being following the method you describe. Today I did some exhaustive tests and determined that something is broken. Have you run the Difference Matter Key Effect in Premiere Elements 9 on a Windows machine? I have posted my test results at
The effect does something, but not what is expected.
Sorry, Larry. I'm not sure what you're going for, so I'm not sure if the Difference Matte is what you should be using.
Here's a description of how the Difference Matte can be used effectively.
But it could well be that you know what you're doing (you definitely seem to know your way around the program) and I'm just not getting it. Sorry if that's the case.
I saw the link you provided below and that prompted me to try the Difference Matte Key Effect. I wanted to shoot a scene in a room and then remove the static room and replace it with another background, while keeping any motion that occurred in the room. That is exactly was happens in your Livedocs link: The boat is kept, but the background is replaced. I first tried using the effect as described above with a fixed-in-place webcam. I shot the empty room, used that as the reference image ( like the image of the Golden Gate bridge (sans boat) in your link and then shot a clip with action in the same room. In a separate video track I provided a different background that would replace the static room ( my version of the scene of Mt Moran and Jackson Lake). This did not work.
I thought there might be a registration issue, perhaps caused by interlacing in the video. Also I wasn't sure how color was encoded in the video. To rule out these possibilities I went to the simple B&W image tests I show in the pdf file that I posted. This was the simplest test I could devise for the effect ... I really don't care about such images per se, I was just trying to do some de-bugging.
My best guess is that the Difference Matte Key Effect is not properly implemented in Elements 9. I note your link is for "After Effects CS3".
Have you actually used the Difference Matte Key Effect in Elements 9? I would like to know if someone else can either use the effect in Elements 9 or else confirm a bug.
Thanks again for your response.