Question Lighting the Areas near Edges of Textures?

Hi all!

I'd want to achieve an effect where my 2D textures have some light glow on their edges. In the attached mock-ups, you can see how the upper-left edges of some bushes are lit with yellow light glow. I want to achieve a similar kind of effect programmatically.

Since I'm new to shaders/lighting, I was wondering what approach would be the best to take here? Should I be using a shader? Normal maps? Something else?

Thanks!