I don't totally know the scope of your question (as in - this is completely server side processing or can be server-side and client-side, etc), but the easiest and quickest solution that comes to mind is to use CSS to position your pointer over the base image at X and Y (top and left). This could easily be done in Javascript - it gets the x and y, and places an image at x and y. If x and y are in pixals, then no converting would be needed for the CSS, just use as is.
Lets say I have 800 by 600 image on my screen. Is their a really simple way to plot an (x, y) point on that image? Very similar to graphing you'd do in a math class, but rather then little dots I'd like to plot that with little images. Easy way to do this?
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