I have a series of images that I want to scale up in increments, eg from 75% to 80%, 80% to 85% etc. I can only seem to be able to scale up from a % to full size. Is there some way I can scale up bit by bit?
Speaking from a graphical point of view, you should never scale an image(especially .JPEG) up larger than it is originally, you'll get jagged edges and squares everywhere. Start with an image that is as big as will be at your full scale, and scale it down to fit on the screen. This way when it is scaled back up there will be no quality loss.
If you look inside the properties menu for each image, there will be a box with a plus(+) sign in it marked position(click the plus sign), you can adjust the scale there, as well as with an action script, or a button(be sure to click the 'element has properties' buttons first though).