What color is snow?

rutt

Even when I compensate a lot and OE and even when I adjust the L curve a lot to blow out the snow it almost always has this unpleasant cyan cast.

For example, here is a shot with auto WB in the late afternoon yesterday with EC +1 and no tinkering:



And here it is after I tinkered with the LAB curves to make the snow more neutral:



I also lightened by steepening the L curve from the light side, blowing out the ski and nearly blowing the snow. I flattened the B curve just where the snow was (on the blue side) to bring it 85% of the way to neutral. It looks better, no? But I'm not sure it's right. Maybe snow really is cyan/blue. Painters seem to think so. Look at Monet's snow sometime. When I look at it out of the corner of my eye right before my brain processes it, it looks blue, but then the brain's fantastic auto wite balance kicks in makes it white.

Perhaps because snow is white (or at least very light) it reflects the sky. When the sky is blue, snow should be blue, too. When there is a shadow on the snow and you can see both sunlit and shadow snow, the snow in shadow looks blue (perhaps reflecting the blue sky) and the sunlit snow looks wite (or more yellow by comparison), perhaps because sunlight is yellow.

Here is a picture I took earlier in the day, during the blizzard when the sky most certainly was not blue:



This is a out-of-camera jpeg. I had EC +1, AWB. Here the snow is almost completely neutral.

Water is blue, and ice can be blue (look at a glacier someday.) Maybe snow is blue? But it looks so much better when it isn't, at least to me. What do you think?

rutt

This is sort of a good topic for Dan Margulis' Color Theory mailing list. I guess I'll cross post it there and report if there are any interesting replies.

DavidTO

rutt wrote:

This is sort of a good topic for Dan Margulis' Color Theory mailing list. I guess I'll cross post it there and report if there are any interesting replies.

Seems like the perfect situation to use custom WB. You've got a ready-made white card!

mercphoto

Your second pic looks more correct. The face looks natural, and the color of the jacket looks more natural. I'd say the predominance of white in the scene is throwing off the AWB, or perhaps the exposure meter. And, as you say, it might be reflection of the blue sky.

Try a white balance adjustment in post by simply using the snow as the source of your neutral color and see what happens (rather than manually adjusting with LAB curves). The suggestion to shoot a patch of snow as your custom white balance was a great idea. As far as I know, and I could be wrong, snow is a pure white.

rutt

DavidTO wrote:

Seems like the perfect situation to use custom WB. You've got a ready-made white card!

That's assuming that snow really is white, which is the very thing I'm questioning.

rutt

mercphoto wrote:

Try a white balance adjustment in post by simply using the snow as the source of your neutral color and see what happens (rather than manually adjusting with LAB curves).

I think I don't know exactly what you mean. I'm guessing that you mean:

1. Set a color sampler point on the snow
2. Image->Adjustments->Color Balance
3. Tinker until the RGB level of the sampler are even?

This is very like using a LAB curve, but with less control. Or perhaps there is some better magic I don't know. (You can see that I was trained to do it the hard way by Dan Margulis.)

mercphoto

rutt wrote:

I think I don't know exactly what you mean. I'm guessing that you mean

Well, my PowerBook with Photoshop is at home, not at work, so I'm going on memory here. I know in the raw converter you can use an eye dropper tool to click on a neutral color and have the white balance set according to that sample. For that matter, you can click on a non-neutral color was well, and get some really odd effects. If you're not in the raw converter I don't know what to do to set color balance, but I'm guessing there is an analogous way to do so automatically by telling PS "this is my neutral color".

If you can do so automatically, it saves some manual effort.

fish

rutt wrote:

That's assuming that snow really is white, which is the very thing I'm questioning.

I think snow is white. And blue.

Check this out:

White snow:




Blue snow:


The defense rests.

rutt

mercphoto wrote:

Well, my PowerBook with Photoshop is at home, not at work, so I'm going on memory here. I know in the raw converter you can use an eye dropper tool to click on a neutral color and have the white balance set according to that sample. For that matter, you can click on a non-neutral color was well, and get some really odd effects. If you're not in the raw converter I don't know what to do to set color balance, but I'm guessing there is an analogous way to do so automatically by telling PS "this is my neutral color".

If you can do so automatically, it saves some manual effort.

Got it. It's a RAW converter thing. I guess I knew about that. I was thinking there was something in the more general adjustmetns I didn't know about.

My brain is now warpped to the point where LAB curve writing comes quite naturally to me. It isn't really the difficulty of neutralizing the snow that I'm trying to get at. It's the effect. In these shots, everything seems to look better when the snow is neutral. But strongly suspect that it often isn't neutral and thet know the truth would be useful in getting the best possible results.

Just look at all the posts from the weekend's blizzard. A lot of them are blue, and Andy hinted that he corrected his a little to get the blue out. (Andy, is this true?)

Sometimes the blue can be nice:

Here is a shot Anne McRae posted today:



Here the snow is very blue. Is it better neutral:



There is some evidence that neutralizing the snow made some of the other colors more realistic (in particular the yellow/green of the pine trees) but it's inconclusive. Anne also posted this lovely image.



I took the liberty of neutralizing the snow and got this version:



In this case the version with the neutral snow does look better to me.

rutt

If snow is really white, it should change color a lot depending on the light. I think that's what you are showing, especially with the purple footprint.

fish

rutt wrote:

If snow is really white, it should change color a lot depending on the light. I think that's what you are showing, especially with the purple footprint.

exactly.



snow can also be brown and yellow. i would not let your children play near snow that is this color. :nono

Andy

rutt wrote:

Just look at all the posts from the weekend's blizzard. A lot of them are blue, and Andy hinted that he corrected his a little to get the blue out. (Andy, is this true?)
QUOTE]

i used custom eye dropper in the raw conversion in acr, followed by a small boost of exposure, just for the snow, in ps cs.

Andy

fish wrote:

exactly.



snow can also be brown and yellow. i would not let your children play near snow that is this color. :nono

<img src="https://us.v-cdn.net/6029383/emoji/lol3.gif&quot; border="0" alt="" > <--actually, busting a gut here!

rutt

andy wrote:

rutt wrote:

Just look at all the posts from the weekend's blizzard. A lot of them are blue, and Andy hinted that he corrected his a little to get the blue out. (Andy, is this true?)
QUOTE]

i used custom eye dropper in the raw conversion in acr, followed by a small boost of exposure, just for the snow, in ps cs.

Which means you think it out to be white. I guess I think so as well. I got this from one of the Dan Marguloids:

The blue cast in snow is correct, that is light reflected from the sky does create the blue cast and because the shadows have no warm light from the sun the problem is always more pronounced. Removing this blue cast is therefore not making the picture more accurate but it does make it more pleasing.

This seems correct to me.

DavidTO

rutt wrote:

If snow is really white, it should change color a lot depending on the light. I think that's what you are showing, especially with the purple footprint.

I vote that snow is white. Pure white. And that it takes on the color of it's surroundings.

In the case of the fence, I prefer it blue-ish. It feels more in tune with the tone of the shot.

Andy

rutt wrote:

Which means you think it out to be white. I guess I think so as well. I got this from one of the Dan Marguloids:

The blue cast in snow is correct, that is light reflected from the sky does create the blue cast and because the shadows have no warm light from the sun the problem is always more pronounced. Removing this blue cast is therefore not making the picture more accurate but it does make it more pleasing.

This seems correct to me.

yup. but if one sets manual wb in the field, you could get the same results, i did that all the time with my sony f828 and f717.

Ann McRae

rutt wrote:

Which means you think it out to be white. I guess I think so as well. I got this from one of the Dan Marguloids:

The blue cast in snow is correct, that is light reflected from the sky does create the blue cast and because the shadows have no warm light from the sun the problem is always more pronounced. Removing this blue cast is therefore not making the picture more accurate but it does make it more pleasing.

This seems correct to me.

Hi rutt (and andy and fish and david and.....)

I've been digesting on this thread, and basically I agree that snow takes on the color of its surroundings. It is many shades of grey, shall we say.

In very bright sunshine, like we have here today - snow is white - 255 white - blown highlights all over my backyard. In the shadow of the clouds or the trees, it is grey/blue/less white.

Last night, at dusk when I was taking those photos, the sky was a great deep blue (the park shot) and that was reflected by the snow. And that was what I was trying to convey.

The fence shot was taken about 1/2 hour earlier - it was overcast/light was flat, sky was blue grey and the snow looked more white, but a different white than the fence, and not pure white.

For my taste, color correcting either of those shots such that the snow reads 255 is not pleasing. Snow only looks pure white to me in sunlight and possibly moonlight (artificial light too?), other times it i some shade of blue/grey.

I believe it is all a matter of what the snow is reflecting.

And I've been looking at snow this year since Oct. 1!!!!!:cry :cry :cry :cry :cry :cry



ann

Ann McRae

An example where white snow is right - this is pretty much straight from the cam:

DavidTO

I actually mispoke when I said pure white, I meant to say completely neutral. Obviously, it is shades of gray.

The fact that snow takes on the color of its surroundings can work for or against. In the case of the fence, as I said, the blue cast works very nicely.

pathfinder

rutt wrote:

If snow is really white, it should change color a lot depending on the light. I think that's what you are showing, especially with the purple footprint.

John, Snow is a WHITE reflector, and like any white reflector it WILL reflect the color of the light it is illuminated by, just like shining a red light on a white reflector in a studio will photograph as reddish in color.

When I was shooting jpegs with my 10D last winter in the snow, I found the images were better if the WB setting was set to shade or overcast rather than AWB. Snow will appear nice and yellow-orange in the setting sun, or very cool blue before sunrise, or sky blue in the shade in the afternoon. Which is right? They are all right - it just depends on what you as the artist determine is correct. Andy even showed over exposing and then pushing the curves in PS to drive the snow completely white to 255,255,255. Right? Wrong? Depends on the artists intention, non?

Shooting RAW lets me adjust the color temperature in Adobe RAW Converter. What I did this last weekend shooting birds in the snow is pull the image into ARC and then use the eyedropper tool in ARC to sample the snow or another neutral color ( light grey is actually better to use than white here according to the book about using ARC by Bruce Fraser ).
http://images.amazon.com/images/P/032127878X.01._SCLZZZZZZZ_.jpg

Once I have used the eyedropper tool on the neutral image color, I look at the color temperature that was set when I used the eyedropper. If I like the color, and the snow reads a very light neutral grey in RGB data I may stop there, or I may average that color temperature with the color temperature that was picked by the camera at the time of shooting. I find this works very well at giving me images that seem color balanced without having to do any color correction once I have the image as a 16bit tiff in PS.

This is the technique I used for color correcting these images shot on a very grey overcast day

pathfinder

fish wrote:

exactly.



snow can also be brown and yellow. i would not let your children play near snow that is this color. :nono

Fish - you bring a whole new level to the discourse regarding the color of snow!!:roll:roll:roll

But you are right that snow can be many colors depending on the ambient light, and the critters that have meandered by.

fish

pathfinder wrote:

Fish - you bring a whole new level to the discourse regarding the color of snow!!:roll:roll:roll

:encore

rutt

I got this from the Color Theory mailing list and I think it's on the money.

Snow is definitely white, in the sense of reflecting all visible colors more or less equally. As you noted, shadowed snow is blue, because sky is blue. If all the snow in an image is in shadow, then it makes sense to set the white balance according to that snow, to mimic what the brain does when presented with the actual scene. If you have both sunlit and shadowed snow in a picture, then it makes sense to set the white balance by the sunlit snow, and allow the shadowed snow to go blue.

What's really odd how the brain works. It will do it's own "auto white balance" for real situaitions but for photographs of them, you have to balance for it.

rutt

rutt wrote:

I got this from the Color Theory mailing list and I think it's on the money.

Snow is definitely white, in the sense of reflecting all visible colors more or less equally. As you noted, shadowed snow is blue, because sky is blue. If all the snow in an image is in shadow, then it makes sense to set the white balance according to that snow, to mimic what the brain does when presented with the actual scene. If you have both sunlit and shadowed snow in a picture, then it makes sense to set the white balance by the sunlit snow, and allow the shadowed snow to go blue.

No sooner to you learn something, than you have eyes to see it and do see it. Last night I was flipping through a magazine and saw two ads one for Rolex and one for T-Mobile with snowscapes. Both have sunlight and shadows on snow and in both cases the hightlights are neutral and the shadows have a blue cast.

Joolya

This should answer our color questions.

rutt wrote:

If snow is really white, it should change color a lot depending on the light. I think that's what you are showing, especially with the purple footprint.

Your question prompted me to do some research and I found a great article written by Hannah Holmes. Pretty much, snow shows up blue in a picture because more light has penatrated it, making it lose the red tones. If you don't quite follow what I mean, check out the article. It really makes sense when you think of what a camera is doing as it takes the picture.

Here you go:
http://www.discovery.com/area/skinnyon/skinnyon971003/skinnyon.html


Hope this helps!! :smooch