Paper Color

Is it possible to set up a rule that will act on scans of yellow paper only?

I write a lot of handwritten notes on legal pads and would like to be able to set up rules for these scans. My handwriting is not going to be legible via OCR so I am not sure how to do this.

That is highly specialized logic. You'll need a program to analyze the image background and determine whether it is yellow. I don't know of anything off the top of my head. I suggest searching the internet at large as this is more than a Hazel problem.