can we draw lines based on the color in the image such that red color in the image is thicker to thick and blue to dark blue is thinner none?

I have microvascular perfusion rgb images. Wanted to see vessels but could not do it because of lot of noise (I guess). Now is it possible to draw lines (as in drawing ROIs) that is computer adjusted such that red color in the image is thicker to thick and blue to dark blue is thinner to none