Quote Originally Posted by Chan Tran View Post
What I am asking is my densitometer like most has 4 readings R, G, B and V but it only uses 3 channel sensor. How did it figure out the V.
What brand of densitometer is it. I have not seen a densitometer that shows "V". You probably need to contact the manufacturer to find out.
If "V" is from the HSV system, then there are some converters on-line that can go from RGB to HSV: http://www.cs.rit.edu/~ncs/color/t_c...HSV%20to%20RGB http://www.javascripter.net/faq/rgb2hsv.htm

The color densitometry chapter in Todd an Zakia describes Equivalent Neutral Density (END) and mentions that if you know the END and Analytic Spectral Density of a dye, you can take that ratio and use it in the ASD/ISD conversion matrix to calculate END.