I have a gif file that is the floorplan of my house. On the server-side, I need a way to modify the gif file so that it shows the current state of the lights. I want a green dot if the light is on, and a red dot if the light off. With maybe a dozen lights on a floor, I can't (don't want to) create every possible combination of gif files to show those states. 2^12 gif files doesn't sound that fun to create. So how can I create a gif file from the floorplan plus the appropriately colored dots on the fly on an IIS server when the page is constructed?
People must do this to construct graphs on the fly, so I should be able to do the same.