I need to be able to focus on an image that is very large. Basically, I want to go to a certain coordinate on an image(that is larger than standard browser size) to show a location and maybe even draw a line going to that point. I have used the gd libraries, but I haven't seen anything that would allow me to focus an image in the way that I have described. I think that I could figure out the line drawing on top of an existing image. Could anyone give me some advice on how to do this, please?

Thanks!