marking and labelling a l*a*b space image

I have an image in l*a*b space. I would like to mark regions with specific l, a and b values. For example all regions with l=80, a=50 and b=90 should be marked and labelled as "C1"on the image. similarly regions matching l=40, a=70 and b=80 should be marked and labelled as "C2"on the image. I am struck as there are around 10 colors I have to find and mark. Any help please...