So, like any webpage, you can send data to the webpage using &variablename=value. Fairly simple process, but adding properties to this particular script could make for a long url. I have tried to make this accessable to everyone, so I'll explain the properties.
image: Sets the image using a URL. Does not support variable urls, so sites like Dropbox won't work. Personal websites and imgur will work though as long as you use the direct link to the .png or .gif.
width: This sets the mask image's width.
height: This sets the mask image's height.
camX: Set's the webcam's x. (defaults to 0 if not set)
camY: Set's the webcam's y. (defaults to 0 if not set)
camWidth: Set's the width of the webcam. (Defaults to image width if not set. The way html5 captures webcam feeds, changing the height doesn't change the aspect of the webcam feed, and instead scales the whole image. To keep things acting in an expected manner, only the camWidth can be set, not the camHeight.)
Here's an example of a fully working url:
http://calibermengsk.com/streamtool...esofthestorm.png&camX=20&camY=23&camWidth=260