I was suprised that a green rice pady would give me a histogram of the 3 primary colors so well seperated.
The hue of your RGB primaries varies from color space to color space, so what is "pure green" ( R=B ) in one color space may have unequal R and B values in another. And as has already been mentioned, finding anything in nature where any two color channel values are equal is pretty tough. In pretty much every color space, foliage green is well to the yellow of "pure" green; the R value will be quite a bit higher than the B value.
