Misusing imageData

The topics in the LiveCode online tutorials include manipulation of imageData, turning a colored image into a grayscale one (this particular example of turning a colored image is located at http://lessons.runrev.com/s/lessons/m/4071/l/25371-vision-how-do-i-convert-a-color-image-to-grayscale). We're not going to do that here. Instead, we'll use the values in the image, mask, and alpha to achieve some neat things that don't change the image at all. In fact, in some cases, we won't even see the image!