Recently at work I had to recreate these pages with little "VH1 style help balloons" over screenshots. It was easy enough to ripe out the individual balloons, but I had lost the positioning of them, the x- and y- offsets.
So I coulda just guesstimated the X and the Y, or try to read it off the big image (more difficult because the sliced out balloons had arbitrary amounts of whitespace), but I came up with a better solution:
var x1 = Math.round(e.pageX - $("#backdrop").offset().left);
var y1 = Math.round(e.pageY - $("#backdrop").offset().top);
I've used this technique before... for example to draw an inviation to the Game Kart Jam I was hosting, I made a simple drawing program, then drew the letters by hand, capturing the coordinates to standard out. Then for the final version it uses that raw data to show my message. When I use this technique I can often have the system out show data in the array initializer format, or sometimes even in program code, which gives the charming sensation of writing a program that is then writing more of itself.