A study in colour - Part 5: Capturing yellow

The colour yellow is difficult to print or display on electronic media.

I have noticed over the years that yellows don't always come out with the brightness or level of detail that I would expect.  It seemed to me that yellows would hit a wall when it came to how bright they could get.  That never seemed to be a problem with the other colours.  To prove this to myself, I took an image with bright yellows and broke the colours down into their CMYK counterparts and looked at the levels of the colours.  You can see the results below.

Yellow-rumped warbler.  Notice cyan and magenta hit the left wall on the histogram and stop, but yellow goes past the wall.  This is because the file is not capable of rendering yellow to that level.

Upon researching the concept further, I discovered that there is truth to the concept.  It seems that the ability of the human eye to see yellow extends past the gamuts of print, film, and electronic media.  Another problem is that the human eye is particularly sensitive to yellow/green hues and so yellows may come across as being brighter than they really are.  This is due to something called the Helmholtz-Kohlrausch effect, which basically states that with equally luminous colours, yellow seems to be brighter than it really is.

The simple fact is that we use materials to present colour to the human eye and that our eyes perceive the world somewhat differently than what colour number theory may indicate.  It is all very complicated, and I don't actually fully understand it all, but I do find it interesting.

Thanks for reading.

Eric Svendsen     www.ericspix.com