At work I photograph rocks/mountains with spray paint markings. Sometimes those markings are a little hard to see, so I would like to increase the visibility of them. Usually, the photos are 95% greytones, and some red spray paint, so I guess it shouldn't be very hard to make the red color to stand out more. It does not matter if the rest of the picture is slightly distorted, as long as it's easy to see the markings.
I have attached a sample photo. As you can see, another problem is that some areas have shaddows/darker areas - are there any simple techniques I can use to minimize the shaddows?
Thanks in advance!