In the Lakeview Elementary Media Center, we have a large, empty, green wall in the juvenile fiction area. About half of the day, it is occupied by K-2 students in storytime, but it is available the rest of the day and between storytimes to use as a "greenscreen".
A "greenscreen" can be just about any color as long as there are few shadows and the surface is smooth (but not shiny). The magic is what you can do with the background using software available on all our student and staff computers.
Here are some READ posters I created on the fly during the recent Parent Teacher conferences, when we had lots of traffic coming through the Media Center. It was so much fun and I explained the process to anyone who was interested.
Here is how I did it.
I set up the Media Center's simple Canon point and shoot camera on a tripod. I put my laptop on a cart nearby and started taking photos of teachers, parents and students. I downloaded the images right away and imported them into iPhoto.
I then opened a new blank canvas in Pages. I located my photo in the Media Inspector and drug it to the blank canvas. I then used the "Instant Alpha" tool under Format. That tool makes the green background transparent.
The next step was to select an image to go behind my photo. I have a collection of READ backgrounds which I purchased with an SEF grant several years ago, so I had the teachers, parents and students select their own. I drug the background (also from Media Inspector) to the canvas and placed it on top of the photo.
I then clicked on "Arrange" and "Send to Back" and adjusted the sizes of both of the layers.
To finish up, I did a screen shot (command/shift/4) and saved the file to a folder. It is not a high quality image, but it is perfect for a web page.
It is a few steps, but students could easily do this, putting themselves on top of the Hoover Dam or an Egyptian pyramid.