I am writing an article about darktable and one of my editing examples is a winter landscape with a lot of snow. I already realized a long time ago that snowy landscapes tend to look very blue and the white balance needs to be fixed. However, I am wondering why winter landscapes mostly look so blue? Is the camera white balance wrong or our human eyes? Do winter landscapes actually look so blue because the now is reflecting the color of the sky, and the human visual system is just making the picture prettier, or is the camera white balance really wrong? I donât seem to find reliable resources about this question on the internet.
Could you post any examples? There are very different kinds of snowy landscapes.
One of the common issues I have had is that snow ends up looking dull and too gray on an overcast day.
There may be some cognitive effects at play, since I think we would usually expect snow to look white and be the brightest element of the picture, since it is, after all, very reflective.
From an editing point of view, I would say that setting proper white balance and exposure goes a long way. Having enough exposure is important. Another important thing is to ensure that the highlights pleasantly transition to white (which is the job of filmic or sigmoid or the like).
Should definitely dig up some old snowy photos and experiment.
AFAIK snow reflects mostly blue light, as explained in eg
White balance (and color grading) is always an artistic choice, there is no ârightâ or âwrongâ. Some images benefit from the blue, especially for ice. Or if there is a nice orange to provide a complementary color.
part is in shadow and can reflects the (blue) sky.
The part in the shadows will tend to blue, even without the sky reflection, compared to the sunny part.
Of course, I have no idea about the kind of adjustments the camera applies (does it ârecogniseâ the blue sky in a landscape?), but it tends to start from the assumption a scene is on average neutral gray.
I always find pictures of glaciers and the like, where the ice is saturated turquoise, almost unreal. But I guess it looks like that to the eye. Never seen one, myself. Maybe similar to turquoise coastal waters
Apart from the reflection of the sky, the ârealâ color of ice is blue. But this can only be seen when there are no or very few air bubbles in the ice that scatter the light.
Just another thing to keep in mind: even if the wavelengths reflected from the snow would be mostly blue, it doesnât mean that they should be presented as such in a well made pixture.
A picture is not a simulacrum of some scene / reality and should not be considered as such. I believe the chromatic attenuation towards white in the brightest parts is very important here to make a reasonable picture.
So, I think there is not an absolute answer to all of this. It boils down to artistic intent, just like when painting such a landscape.
Itâs really hard for people who donât do much photo software processing to get this, I think. It seems like cheating, and I admit I felt this way myself at first before learning a tiny amount about the visual system and photographic sensors and film. SOOC seems somewhat meaningless when you have a bit of this understanding. Still, I guess you can aim for more or less fidelity to the scene if you were there.
I find this depends a lot on the cameras auto WB. I donât get a lot of snow here in Australia, but when I do get a snowy landscape my Nikon, on auto WB is inclined sometimes to balance the snow to white. Which especially at blue hour for example looks very muddy, and I end up making it bluer in processing.
Iâll see if I have an example later.
Essentially the light is traveling down through the snow or ice and as it gets deeper, more and more of the light is scattered. Over a reasonable distance, with enough light being scattered, the particles of light that do emerge from the bottom layer of snow/ice tend to be made up of blue light. Much like the long path through the atmosphere creating the blue sky, the long path through the snow, creates blue snow!
This is the answer provided by @Tamas_Papp and that is all you need to state. Now you could also ask why brides dresses are blue when they are photographed in shade?
Some materials use whiteners that react to UV light causing a blue fluorescence that is visible to the camera but not the human eye. With the advent of color photography for weddings and I guess a few blue words from irate brides most white wedding dresses no longer suffer from this problem, but it was very prevalent in the 1970âs. Still occasionally rears its ugly head though.
So, clear-sky daylight isnât just the sun, itâs also an amalgam of various diffraction and reflection of the sunâs radiance. Mid-day, a cobalt-blue sky is a significant contributor, and where I think you get the majority of your notion. That blue is the result of Raleigh scattering:
which turns tables at sunrise and sunset and give dominance to the other end of the spectrum. Observe snow at these times, tell us what color it is thenâŠ
The light and its component wavelengths is what color starts as, so itâs worth picking at it first when analyzing your color perceptions.
This, incidentally, is similar to the reason why white balancing on white surfaces (paper, fabric, paint or others) often gives wrong results. While they may appear white, they are often what is called optically white, which is really a kind of blue tint.
Indeed. White fabric is often dyed blue with a slight tint, in the factory and at home. Cameras may pick it up a bit more.
But unless color accuracy is required (eg items in a printed catalogue), WB and color grading are an artistic choice, there are many reasonable paths from the same RAW.
@betazoid, depending on the audience of your article, multiple (3-4) edits of the very same image could be an interesting demonstration of darktable.
Iâm not convinced that the assumption is true. The human visual system is quite good at distinguishing colours, but poor at assigning absolute colours. We are good at judging âthis is bluer than thatâ, but poor at judging âthis looks blueâ.
If we are sitting indoors, with âwarmâ illumination (low Kelvin), with eyesight adjusted for that, then we look outside through a window on landscape that is illuminated by cooler daylight (high Kelvin), it will look blue.
Conversely, if we walk outside at dusk, and encounter a house and can see through the window to an electrically-lit room, it will seem to be yellow.
What is different about winter? (1) We psychologically associate colder with bluer. (2) Winter sun is low in the sky, casting longer shadows than mid-day summer, so a larger proportion of the landscape is in shadow, illuminated by the sky which is bluer than the yellowy sun, even on cloudy days. If we judge blueness or yellowness by the ratio of shadow/sunlit areas, winter landscapes will seem bluer.
Currently, the image from my right eye is slightly bluer than the image from the left. Both eyes have replacement lenses, but cataracts also affect other components of the eye. I donât know which eye is more correct. I suppose an ophthalmologist could tell me, after peering closely into each eye. But the truth is, it doesnât matter. My brain adjusts to the difference.
I agree with this and your following explanation. Often when given a playraw image on this forum I first set the WB to daylight to see what the lighting presumably looked like before we make our interpretation of what it should look like.
