Loading .PNGs for a GUI?

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So I just started learning ROS and I was wondering how I could load images, specifically .PNG files, for a GUI. The idea is to create a display that the user can click on to publish a specific topic. I have some experience working with SDL and am using SDL's functionality to create a window and display the images. Right now, the images are stored within a file labeled "media" within the package, and the node fails to find them when executed.

How would I modify the CMake file or the package itself to load the images? I have tried looking at the turtlesim package used in the tutorials, but I can't seem to find the process used to load the images.

Any help would be greatly appreciated, thank you!