How can I know what is ideally neutral in a picture, in order to set white balance?

Question

According to my understanding white balance is procedure that removes effect of colorful lengthening. It makes picture like it was lightened with ideal white color light. Please, correct me if I'm wrong.

To adjust color with White Balance Tool in Adobe PS we need to pick color in the picture that in white light is neutral (currently it is not because of colorful light). Neutral means all basic colors RGB has the same values. It might be absolute white - 0,0,0 or black - all max or different darkness of grey. Please correct me if I'm wrong once again.

But how to know what is ideally neutral in my picture? Can I make two photos - with white paper and without it and according first one set second one white balance. Is this right approach? Can we assume that snow is always white? If I take snow in shadow and snow in light as neutral I will get different white balance result. Why?

Answer 1

It makes picture like it was lightened with ideal white color light.

Yes.

To adjust color with White Balance Tool in Adobe PS we need to pick color in the picture that in white light is neutral.

Yes. Normally you use a grey zone (instead of a pure white or black, becouse thoose could have clipped values).

But how to know what is ideally neutral in my picture?

Ok you probably do not have any neutral gray in your entire scene, so you take a reference shoot with a gray card: https://en.wikipedia.org/wiki/Gray_card (Yes, you can use a good sheet of paper :oP)

Then you save that reference. In a RAW process you can save the "recipe" for that light situation. In photoshop you can use the "last used" white balance.

But besides a white balance with a gray card you can set the balance taking a picture of the light source: Color issue: studio images have a pink hue

Answer 2

To answer your question about different white balance results from snow in light and shadow: snow that is in sunlight will have a warmer light falling on it, while the light that falls in the shadows is reflected light off the sky, so tends to be more blue, so cooler.

You need to pick something that is not blown out. So snow, if the RGB values are all near 255, will probably not give you much correction - if one or more of the values is blown, then the relative difference in values will not be correct.

In any case, you don't necessarily want to find something that is perfectly neutral, and then correct it fully, because it will take all the warmth out of the image. Often you want that. So it's a subjective thing - find something close to neutral, apply the white balance correction and then use your judgement whether it improves the image or not. If it overcorrects, try another spot, or use the correction and dial it back some until it looks right to you.

Answer 3

According to my understanding white balance is procedure that removes effect of colorful lengthening. It makes picture like it was lightened with ideal white color light. Please, correct me if I'm wrong.

For the most part, that's right, but it has a subjective element to it. White balance is used to make things "look" like they are the correct colour. Often this means, to make white things "look" white rather than to have a colour cast.

Sometimes, however, there are multiple sources of light in a scene with different colours, so it's hard for the brain to make sense of what should look white and what should look coloured, and so there is a bit of subjectivity to the choice of how to set colour balance. There are also some situations where a strong colour cast is expected, and removing it would look "wrong" - for example, shooting a sunset where you expect the clouds and land to be bathed in orange, or shooting underwater where you expect everything to be a bit blue.

So you can take a methodical approach to get "correct" white balance, but in some situations it can still look wrong - or you can adjust it until it looks right, even though technically you still have a colour cast.

Another thing is that to a certain point, the eye forgives a colour cast (your brain corrects for it), but if you exceed that point, it starts to look quite wrong. This leaves room for some creativity.

The most reliable methodical approach is to get a gray card (18% gray, typically, so it's not normally overexposed when things like human skin isn't), and place that gray card where the subject is, so that the light that would hit the subject hits the card. So in other words, put the card in front of or next to the subject, ensuring that it's in the same light as the subject. Then you take a custom white balance pointing at the card, marking that as neutral.

This may be possible for some types of photography but for other types this is impractical. You can go with auto white balance (you can always adjust later, and if you use RAW this will be lossless), or set a preset white balance based on the lighting type (tungsten, flourescent, daylight, cloudy, etc).

Answer 4

Different sources of light have different hues that the camera picks up due to their temperature. For example, a candle has a low temperature, resulting in a redish/orange tint on the photo. Another example is florescent light, which has a greenish white tone to it. Then you have a clear blue sky which has a blue tone to it. (There are more sources which cast different shades but you get the hang of it).

White balance is used to counteract those tones to achieve a neutral white. However, it can also be used to achieve whatever tone you want. For example, if you are shooting a person in daylight and want to make their skin tone more flattering, you might increase the yellows. So I guess that in the end white balance is just changing the hues to achieve an ascetically pleasing tone cast over the image.

When I am in photoshop or lightroom, I don't necessarily use a tool to find the exact perfect "balance". I do it by eye. I started out by experimenting and figuring out which colors can be used to counteract the "incorrect" tones that were present in the original photo. I sometimes pick an object or subject and use the sliders to get to my desired outcome. I feel that this method is more helpful than "picking the perfect white balance" because often I find that I don't want that perfect balance. I tend to like slight hues to convey a mood. of course that is just my stylistic opinion but I feel like practicing and experimenting allows you to fully understand why and whats changing.

Answer 5

Possibly the only way to ensure you have something absolutely neutral in the scene is to get a white balance reference card of some kind. 18% gray cards can work, but knowing they're color-neutral is another thing. There are expensive tools like this, such as the WhiBal or the ColorChecker Passport. And if you have the camera set in RAW, you simply take the picture twice, one with the reference card in the shot and one without, and after you've white-balanced the shot with the reference, you then duplicate that setting on the shot without it (i.e., use the setting synchronization feature in Lr or ACR).

However. This only makes your white balance match the color the object is in white light. Not necessarily the color it looked like in the lighting conditions you were shooting in. Sunsets, for example, warm any scene with a gold glow, and white balancing with a reference is liable to lose you that golden quality that marks it as a sunset scene.

So, getting an "ideally neutral" value to white balance from may not actually be the ideal way of dealing with white balancing. Sometimes adjusting "by eye" in the software until it looks right will work better. References are when you need the color of the object to match that of the image exactly--and most typically under studio conditions where once you've got everything set up, and all the subsequent shots can use the same correction.

Answer 6

My understanding is that accurate white balance is only desirable in fashion or product photography where nailing the color perfectly is important. In nature/landscape photography we are more interested in "pleasing" color...