Click inside depth image and show value.

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What is the "best" / fastest way to implement a simple application inside ROS where I can click inside an image (e.g. depth image) and I will get the output of the corresponding pixel? I saw that there are some functionalities for mouse pointer callbacks in OpenCV and yesterday I used GLFW to do such an application, but it took me quite a while to do this.

So I wondered if there is some ready-to-go ROS package which I can use for this?