White Balance
August 13, 2008
Is there such thing as perfect white balance? Some people worry over getting white balance technically correct. And there are products on the market such as Expodisc that try to do exactly this. In my opinion however, you don’t need to obsess over white balance. Why? Because our perception of color is a guess to begin with.
The following picture appears to be a “white” business card lying on a black background.
I also happen to have many other “white” business cards. By themselves, they all look white. But when placed side by side, it’s apparent that they are all really different shades of (off-)white.
Two things to note here:
- Many white objects aren’t truly perfectly white.
- Despite that, these objects appear white to our visual system when viewed in isolation.
Our visual system has to guess the color of objects since the input is ambiguous. A white card under slightly green light will reflect slightly green light. So will a slightly green card under white lighting. Multiple scenarios can lead to the same visual input. Our visual system will nevertheless make an educated guess as to the object’s real color (these guesses tend to be very good) and that’s what we perceive.
When it comes to setting white balance, I wouldn’t worry over getting white balance 100% correc. In a mixed lighting situation with two or more different light sources of different colors, there is no ‘correct’ white balance for the scene as each light source has its own correct white balance. Perfect white balance is not always possible and it isn’t even necessary. What I would strive for is to make the appearance of the final image fit your intent. If it looks right then it looks right- it doesn’t need to be any more complicated than that!
Do white objects even need to appear white?
There are some cases when the correct white balance does not make white objects appear white. There are certain lighting situations where our visual system’s “white balance” won’t completely adjust for the lighting. A good example is golden hour, which is named the way it is since everything appears to pick up a golden tinge shortly before the sun sets. In this case you don’t necessarily want to make white objects appear perfectly white if you want to maintain the golden tinge of the original scene.
Filed under: color correction, color science, still photography |
I agree with what you are saying about white-balance. What is strange though is that it is not poosible not to use white-balance (all camera’s I know require you to choose a setting). I have always wondered what I would have to choose if I only wanted the actual colors (the actual color frequcncies that objects transmit when the image is taken in stead of the frequencies objects ’should’ transmit) to be recorded as good as possible.
Another idea is to apply differente white balance for different parts of image.
To not distort the image by suddenly changed white balance form pixel to pixel, one can, for example, make only linear dependence of white point color from x and y coordinates.
A cheesy away to achieve different white balance for different parts of the image is to run the filter with multiple settings on individual duplicated layers. Then use masking to reveal the right layer/filter setting combination.
Like I just expressed in my email, you should make a plugin that allows you to selectively adjust the color temperature using a layer mask. Do it the right way; don’t run the plugin several times and combine layers.
To Marnie: You will not like colors from camera without white balance. It is all shifted to green color as you can see on unprocessed RAW photos. BTW. You can have correct white balance even in mixed light conditions but just for one (small) white area.
Wow for me white is white, thanks for telling me off
And white / black is not a color, rather a base for color to be blend on.
Different shades of white color.