civilized ku # 2866 ~ they give us those nice bright colors
Wednesday, February 4, 2015 at 09:30AM 
fresh snow ~ Au Sable Forks, NY - in the Adirondack PARK • click to embiggenMy attention was recently drawn to the picturing idea of blue snow - the blue snow as seen in the shadow areas of sunny day winter pictures. The instigator of my eventual rumination, re: blue snow, was a picture article in our Sunday newspaper regarding the chance that winter offers "to marvel at a palette of colors...".
The author of the pictures and article is a staff picture maker (if such a thing exists anymore) or, at the very least, a picture maker whose byline appears quite often on pictures in the newspaper. With his pictures, he was encouraging people to get out and "... look for those purples and blues that make the snow rich in color...".
To be certain, his pictures area quite "rich" with vibrant blue snow. And, I am quite certain that he came by that color honestly, which is to write, without any Photoshop tomfoolery. I am also quite certain that most of the viewers of his picture will like them, in no small measure because they are quite vibrant / rich, color wise (not a criticism, just an observation). However, I am equally certain that, if those viewers are moved to go out and "look for those purples and blues that make the snow rich in color", they are apt to be quite disappointed.
As any astute picture maker knows, both film and digital sensors (more so than film) are able to "see" light in the Ultra Violet wavelength spectrum. So do butterflies, reindeer, some species of birds, and even sockeye salmon, to name just a few. Consequently, unless those seekers of purple and blue snow have some sort of mutant vision, all they are going to see is white snow. The exception being snow which is lighted by direct warm late day sunlight.
In the good ol' days of film, many a picture maker employed a UV filter to reduce the influence of UV light when making a picture. I assume the same could be done in the digital picture making domain. The digital picture making domain also has the capability of adjusting White Balance when making a picture - the cloudy day setting significantly reduces the blue color to be had on cloudy days and in shadows. However, that setting may also move the color balance in the direction of too much warmth in other areas of the picture.
In my case, I make white balance adjustments when processing a RAW file and subsequently fine tune the picture in Photoshop. I leave a fair amount of blue in the picture at the RAW processing stage and, by the means of making a selection of the blue snow shadows and the use of the Hue and Saturation tool, I move my pictures toward what the human eye perceives rather than what the camera "sees".
This adjustment / correction procedure does not mean that I eliminate all of the blue color to be seen by the camera in the shadows. However, it is reduced significantly, because, in some cases and under some conditions, my human vision is able to see a small hint of blue in the shadows. Although, that usually takes a fair amount of concentration directed specially at looking for the blue color.
In any event, my intention in reducing or in some cases totally eliminating "blue" snow is to reproduce a more faithful / true representation of the real.
Reader Comments (2)
Mark, please allow me to opine differently: While snow itself is white (technically it's transparent, but reflects all wavelengths equally and therefore looks white), the snow in the shadows - according to my observations - looks indeed blue. It does so because it reflects the blue light of the sky in the absence of the 'white' light of direct sunlight. UV light might amplify this effect.
Which of course does not invalidate your decision to tune down the amount of blue that the sensor captured for the shadow areas. In the end it has to be pleasing to the viewer's eye.
My first reaction was the same as Markus... sky reflection... the same effect that makes lakes look blue.
But I do like the version without the deep blue as it just feels more "right".