If you'd like to know more about the essential role that light plays in photography, then you’ll love our course, A Photographer's Guide to Light. In this lesson, you’ll find out why white light isn’t actually white.
A Photographer's Guide to Light: Noticing Colour
Cameras and Eyes and Brains (Oh My…)
A camera system functions in a similar way to our eyes. They both have lenses to focus the light, and they both have a device to regulate how much light is entering the system: an aperture on the camera, and the iris in your eye.
Each has a system for gathering and interpreting information about the light that’s entering the system. Your camera has a sensor, and your eye has the optical nerve. And in terms of colour, they both work in a similar way too. Our eyes have cones that are most sensitive to three colours: red, green, and blue. Even though we have more red cones in our eyes, we’re most sensitive to green light. Similarly, in almost all cameras, there’s a colour filter that sits over the photo sensor that only passes one colour to each pixel.
The camera's computer knows what pixels are behind the colours, so it takes the data and produces a colour image. Your brain works in a very similar way. That said, our brains are much better at putting the world around us in context in terms of colour. Most of the time, these differences show up when you’re dealing with white light.
Look at a white piece of paper under halogen lights: it looks white. Look at the same piece of paper under fluorescent lighting, and it still looks white. Take the paper outside, and it will still look white in direct sun shade and under cloud cover. The 'white’ light is different in all these examples, but your brain is very good at sorting it out and interpreting the colours properly.
What Is White Light?
As you probably learned in school, white light is made up of all the colours in the visible spectrum. You can take white light and shoot it through a prism, and you will break the light apart into its pure colours.
You can also take red, blue, and green light, combine them together, and your eyes—and probably most cameras—will see white light. White light has more to it than red, blue, and green. It has all of the frequencies of visible light. The colour temperature of white light depends on the balance of these colours.
Modern cameras are quite good at determining white balance automatically, but, if it's set wrong or your camera guesses wrong, white objects do not look white.
Recording in RAW Formats
If your camera has the ability to record RAW data files, you probably should whenever you can. With RAW, you have a direct dump from your camera's image sensor, and you have a lot more room to push things around in post-production without nasty artefacts showing up in the image.
In a JPEG, the adjustments have been baked in, and then a lot of data is lost to compression to keep the files small. When you make adjustments to your JPEG photo in post-production, you have less room to push and pull the values around before the image starts to look bad.
JPEG isn't terrible, but RAW gives you far more options in post-production, and when it comes to colour, RAW is the better bet.
Lighting From Multiple Sources
What happens when you have mixed lighting from two or more sources that have different colour temperatures? Now things get interesting.
In this render, there’s some overhead lighting which is quite warm in colour temperature, probably close to 3,500–4,000 Kelvin. And then there are some windows to the right which are closer to daylight, so around 5,000–6,000 Kelvin. The camera—or the virtual camera in this case—is set to daylight white balance.
The light coming in from the windows looks pretty neutral, and it looks white when it shines on a white object. However, the overhead lighting looks yellow, so if you had to take a photo in this kind of environment, you’d have some colour issues that you have to deal with. One way you can deal with it is to try to isolate the light sources.
For example, you could turn off all the interior lights and work with the colour of the light from the windows, as above.
An alternative thing you could try is closing blinds or blocking the window light and dealing with only the light fixtures, like in the picture above. One problem that you may run into is differences in the interior lighting colour temperatures.
In this example, the two rows of interior lights are different temperatures: one is a warmer white and close to 3,500 or 4,000 Kelvin, and the cooler row is around 5,000 to 6,000 Kelvin. This can quite often happen in offices where they have overhead fluorescent lighting, but sometimes with mismatched bulbs in the same fixture.
Back to the window light example, one way to make this look good and balance out the light is to add some artificial lighting. That might be a strobe or flash, which are usually around 6,500 Kelvin—they’re a pretty close match to daylight.
In this situation, the interior lights are off, the window shades are open and then behind the virtual camera is a virtual softbox to fill in the front of the little group shot.
Window Light and Interior Lights
You might not be able to kill interior lights or cover window light. One way to counter this is to add some front fill flash that's somewhere between these two lighting sources.
That's what’s been done here, using a colour that's not quite as orange as the overhead lights, and it's not quite as blue as the window light. With a little bit of colour balancing, which you can do in-camera or in post-production, you can get this to look pretty good.
The overhead lights and the window lights are never going to look perfect unless you spend a lot of time in Photoshop. Either one will look too orange or the other will look too blue, but you can get it pretty close to your subject, and quite often that's the most important thing.
Here are some of the takeaway ideas from this lesson. First, try to isolate the light sources. If you can remove one of the light sources causing a colour discrepancy, that's going to help your colours to be evenly matched. Another idea is to try to recompose the frame so that your subjects are a good distance away from both the lights with differing colour temperatures. This will allow the light to basically mix and create an average colour temperature between the two sources, so that they're evening out on your subjects.
Sometimes, you might be able to swap light bulbs, but quite often that’s just not practical, particularly in offices. You can get pretty wide rolls of gel filter, though, and photographers sometimes use that to gel lights to get them to match.
If none of that works, then try some artificial lighting, like strobes, which can be extremely bright. That way, you can try to overpower the light sources, or create a mix of light to even out the exposure and colour. You may not be able to control all of the background elements in terms of what colour temperature light is hitting them when you're using strobes, but as long as you can dial in the colour on your subject, that's the most important thing.
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About the Authors
David Bode created the video course that includes this lesson. Dave is an expert on video and audio production, and he lives in the upstate New York area. He works as a camera operator, editor, inventor, motion graphics designer, recording engineer, and studio musician.
Marie Gardiner wrote the text version of this lesson, and it was edited and published by Jackson Couse. Jackson is a photographer and the editor of the Photo & Video section of Envato Tuts+.