Your YELLOW is NOT my YELLOW!!!!!

Everyone has his own unique world, each individual has a distinct perception, not only the way each one looks at the things but also the colors in which we see. The most fascinating thing I realized was that each individual has his own paint brush and color palette using which he paints the world around him. The only misfortune is that he cannot color on his own will. The other way to put things is that there are no colors at all; there are only wavelengths that we sense and process to form colors.

Having analyzed this fact, I was keener to find out the reason behind this cause. We say that almost everything is coded into our genome, so there should be something peculiar which should be tapped in order to find the correct reason behind such a cause. So I tried to find out the color sensing organ or pigment inside a human eye.

The color sensing entity in a human eye is cones cells, which actually senses the wavelengths and then preprocessing results in the creation of colors.

In fact, OPN1LW gene is responsible for Red color, OPN1MW/OPN1MW2 for the Green color and OPN1SW for the Blue color. Genes for red and green colors are found on X-chromosome whereas; blue color gene is found on chromosome no 7.

Cone type	Name	Range	Peak wavelength
S (OPN1SW) - "tritan", "cyanolabe"	β	400–500 nm	420–440 nm
M (OPN1MW) - "deutan", "chlorolabe"	γ	450–630 nm	534–545 nm
L (OPN1LW) - "protan", "erythrolabe"	ρ	500–700 nm	564–580 nm

Humans possess trichromaticism i.e. they can distinguish between the three different wavelengths due to the presence of three different opsins discussed above. Of these, blue color pigment is mostly conserved and is most primitive as on 7 chromosome and therefore the color blindness of blue color is very rare as compared to others. Also color blindness of green and red is most common in man as the genes are X-linked, therefore women have an advantage.

Each of the three standard color-detecting cones in the retina -- blue, green and red -- can pick up about 100 different gradations of colors. But, the brain can combine those variations exponentially; the average person can distinguish about 1 million different hues. It is also estimated that 2 percent to 3 percent of the world's women may have the kind of fourth cone that lies smack between the standard red and green cones, which could give them a colossal range. A true tetrachromat has another type of cone in between the red and green -- somewhere in the orange range -- and its 100 shades theoretically would allow her to see 100 million different colors.

Another fact which I came across was that on an average a human eye has 4.5 million cones cells which are responsible for the color intelligence but there are 90 million rods that perceive luminance changes. This means humans are about 20 times more sensitive to contrast or brightness changes than color differences. This is also in accordance with the argument that environment affects the color perception.

Now, Coming to the explanation of the term "Your YELLOW is different form my YELLOW!!!!!. Actually there is big difference in the activity of the enzymes and their expression at the genetic level. So, the only reason I can see is that every individual has his own values of rate constants of the enzymes, different level of expression and regulation of genes. So each of the opsin cells and the enzymes they use will be different for each and every individual creating this ordinary but extraordinary effect.