Retrieve image coordinates at mouse cursor in Preview.app I want to measure the precise pixel coordinates within an image where the mouse cursor sits.

Are there stock OS X or third party tools that can easily do this?
You can do this simply by dragging from the desired pixel to the upper left corner of the screen. This will create a selection rectangle, and the size of that rectangle is shown in the screen. Since the rectangle can only stretch until it reaches the origin (the corner), its size will be the same as the pixel coordinates you're looking for.