I have a question regarding color densitometer whether reflection or transmission type. I know all of them only have 3 sensors and only measure the R,G and B. They use the RGB value to compute the V value. I wonder is there a formula to do that? I know if the reading is 1.00, 1.00, 1.00 on all 3 color channels then the V is also 1.00 but what if the RGB values are different? Just and average of the 3 or is there a weight for some channels.