October 2016

Oct 2016

Color Temperature of Your Lighting

In photography, video and all graphics in general there are so much more parameters to consider than just exposure, meaning lighter or darker image. One of them is color temperature, or white balance. It's about what we consider "white" - a frame of reference, especially concerning light source and so all the objects lit by it. It's not real temperature, but we measure it in Kelvins. Paradoxically, lower color temperature values (like 3000K) mean colors that we call "warmer" - more towards yellow, orange or red. Higher temeratures (like 7000K) mean "cooler" colors - more towards blue. Values like 6500K are considered equivalent of a sunlight during the day, while light bulbs usually have around 3000K. Color temperature of your lighting is important when you work with colors on a computer. They recommend to use 6500K light source for that purpose.

I decided to make an experiment. Below you can see photos of part of my room, with a test screen displayed on my monitor, piece of my wall (behind it, supposed to be white) and a piece of furniture (the right part, also should be white). The monitor is LG 23MA73D-PZ, with IPS panel, calibrated to what I believe should be around 6500K (setting Colour Temperature = Warm2).

Left column shows a photo taken in the middle of the night, with lighting by LED lamps having 3000K color temperature. Middle column is the same scene lit by different LED lamps having 6500K. Finally, right column show a photo taken during the day, using only sunlight.

The only remainig variable is white balance of the photo itself. That's why I introduced two rows. Top row show all three photos calibrated to same white balance = 6500K. As you can see, the image on the screen looks pretty much the same on all of them, because monitor emits its own light. But the wall and the furniture, lit by a specific light source, seems orange or reddish on the first photo, while on the other photos it's more or less gray.

Our eyes, as well as cameras can adjust to changing color temperature to compensate for it and make everything looking neutral-white again. So the second row shows same photos calibrated to white balance of the specific light source. Now the wall and the furniture looks neutral gray on all of them, but notice what happened with the image on the screen when light was 3000K - it completely changed colors of the picture, making everything looking blue.

That's why it's so important to consider color temperature of your light sources when working with color correction and grading of photos, videos or some other graphics. Otherwise you can produce an image that looked good at the time of making, but turns out to have some color cast when seen under different lighting conditions. Of course, if you just work with text or code, it doesn't matter that much. It is more important then to just have a pleasant lighting that doesn't cause eye strain, which would probably be something more like the 3000K lamps.

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