Image pixels of RGB frame to x and y coordinates in camera frame ( in Gazebo simulation)

edit

Hello, I am using Kinect sensor plugin in Gazebo. Since it is in gazebo, I know the camera intrinsic and extrinsic parameters without calibration.

I have u, v image pixel coordinates from RGB camera in Kinect and I wanted to convert it into kinect frame as 2D coordinates (x and y).

I am getting pointcloud data as kinect/depth/points which gives 3D point but I need in 2D plane. Can I able to do lot easier by avoiding depth registration?

Any help!!