Script to detect and select simple shapes?

[tomatoSauce23]

I'd like a plugin to be able to detect and then select simple shapes in a layer or image. So there is a green square in lots of pictures I'm processing and I have to mark them every time they occur, so I do this manually using the Rectangle tool. The squares are always of a similar size and colour. Is there a plugin that could detect squares within a certain size-range and colour-range and then select them? If not, how difficult would it be to write a script like that, given that I have some programming experience but not in Python?