How to Capture a single image from Webcam using Python and Opencv ?

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Hello, if in your book something about Setting coordinates of object on a Picture ?

I 'll explain you my problem or my idea :) I want to recognize apps with a camera on my Phone Home screen and set and return the coordinates of these apps . this Coordinates will help my robot to move and touch or open my app . That is my robot should know based my camera where the apps are and can move ( x, y direction ) to open these apps .

thank you in advance