I am a beginner in Latex, trying to use it for an industrial document. I need in one case to use the picture of a device, say looking as a round clock. I am looking at a way to add a number of arrows, pointing inside the picture to points ie the figures indicating 1 am, 3 am 5 am, etc, with the arrows placed approximately radially regarding the clock. The end of the arrows that would be outside of the picture would need to be associated to a caption...such as "recommended position B of the indicator..". I thought this would be relatively easy to do with tikz, and nodes, but could not figure a way to locate the nodes inside the picture. The tip of the arrows should be located accurately inside the picture, therefore placing them in a mechanical way driven by a diameter and an angle would not work well. Any suggestions?