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How to Use Color Temperature in Black and White Conversions

Digital photography has opened up enormous possibilities for black and white photography. The ability to first shoot in color and then convert the image to black and white offers photographers a way to express themselves in ways that reach beyond the influence of color. Well, for the most part.

You see, advanced black and white conversions take advantage of the different luminance values present in our RAW files so that we can individually manipulate those values after we have converted the color image to black and white. Usually, this is done via the HSL (BW) Panel in Lightroom or other processing software.

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But there is one ingredient of the black and white pie that gets constantly overlooked during the average photographers (let’s pretend) black and white conversion process; color temperature. I know, the operative word here is COLOR and black and white photos…you know…don’t really have a lot of color.

In this article, we’re going to take a cruise aimed at getting a little closer to understanding how much of a role color temperature plays in our digital black and white conversions. We’ll look at how we can leverage this constantly neglected aspect of digital black and white photography so that we have many more opportunities to make even more impressive monochromatic images.

I also intend to make at least one black and white related pun before the end.

Let’s get started!

A quick refresher on color temperature

When we talk about color temperature, we are referring to the hue-based Kelvin scale (there’s a temperature-based one too) which measures the hue of color and thus relates to white balance; which is the theoretical absence of color cast within an image. More blue or “cool” colors have a higher Kelvin number, and more red or “warmer” colors have a lower Kelvin number.

“Adam…but wait! Most image processing software shows lower Kelvin color temperatures as blue and warmer colors as red!”

Yes, you are precisely correct. You paid excellent attention in science class!

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In short, the color temperature sliders in most photo editors are in fact reversed from the true Kelvin scale. From what I’ve gathered, this inversion is due to the approach that white balance adjustments in digital photography are based on “compensation” rather than direct cooling or warming of colors. This means that if a photo is “cool” out of the camera, we will tell the software to “warm it up” by increasing the Kelvin value to bring the white balance closer to the original scene. Thereby, making the photo perceptibly warmer.

Yeah, it’s confusing.

Luckily, we don’t have to worry about any of that.

For our purposes, we are just concerned with how the cool or warm the colors are within the image regardless of actual numeric Kelvin temperature.

Thank goodness for that.

How color temperature affects black and white photos

The remainder of this article assumes that you are shooting in RAW format or at the very least in color JPEG.

We need the color information from the image file to exploit the impact of color temperature on luminance values after the black and white conversion. This means it is imperative that you do not shoot in a dedicated monochromatic mode.

Got it? Good.

Now that we’ve got that out of the way it’s time to experiment.

Let’s first convert an image to black and white in Lightroom Classic CC and see what happens when we begin to adjust the color temperature. I just happen to have a photo ready to go right here. It is a RAW file with a relatively well-balanced color temperature that I converted to black and white.

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Color temperature slider set to 5050K in Lightroom

First, let’s slide the color temperature slider entirely to the left and “cool” the image.

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Color temperature slider at 2000K in Lightroom

Next, we’ll move the color temperature slider all the way to the right to “warm” the image.

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Color temperature slider set to 50000K in Lightroom

From this, we can see that there are some readily apparent changes in contrast based solely on the adjustments in color temperature.

So, what exactly is happening here?

Let me show you.

Have a look at the original histogram with conventional white balance:

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HIstogram with normal white balance

Now with a much cooler color temperature…

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Histogram at 2000K

And lastly, with warmer color temperature.

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Histogram at 50000K

When we cool down the image we are causing the colors to become more blue, purple and magenta in hue; hence the shift in the histogram and resulting contrast change. The same is true for the warmer color temperature where the photo becomes more red, orange and yellow.

What we are doing is setting a bias towards certain colors which in turn augments their luminosity when converted to black and white. The benefit here is that these drastic changes in color temperature allow us to make some impressive adjustments to the luminance values beyond what might usually be possible once you have converted it to black and white.

Practical applications

Advanced digital black and white conversions rely heavily on specific adjustments in luminance values based on color information contained within the image file. If we increase the amount of a particular color within an image, we then have more latitude in manipulating the brightness values of that color in relation to the other colors within the photo.

Here are three separate versions of the Golden Gate Bridge photo from earlier. The first photo was processed using the HSL/BW Panel to brighten the bridge and darken the sky.

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Next, I went to work on the 2000K version from earlier. Seeing as the blue tones had skyrocketed, I was able to achieve some interesting results.

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Last but not least is the warm-toned version which clocked in at 50000K. Which if you recall, would make the photo cooler instead of warmer if we were operating in the world. However, we’re not. This is photography.

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These extreme swings in color temperature are useful almost exclusively in the domain of black and white digital photography. Outside of that, the only result will be gruesomely unappealing white balance.

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I mean really unappealing (caption)

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Just look at it…terrible.

Ok, I’ll admit that maybe I low-key like that last one.

Final thoughts on color temperature and black and white photos

We can get caught up with the idea that there are certain “rules” which must always be adhered to when we process our photos.

Nothing could be further from the truth.

While it’s true that color temperature plays an important role in rendering colors within your image accurately, we must remember that we are still allowed to paint outside the lines whenever we choose. Perhaps the benefit of this free-thinking mentality is no more apparent than when it comes to working with our black and white photos.

Making drastic changes to the white balance of your black and white images is not only allowed, but it can make for some exciting outcomes and boost your creative thinking.

Even though your mind may not immediately jump to color when you think of black and white photography, the fact remains that even though we may not see color within a photo, the inherent color information remains (as long as you shoot RAW) and that information is still wholly adjustable, including white balance. The role color temperature plays in processing your photographs is never black and white. See, I told you I would work that pun in there somewhere.

Experimenting with some interesting black and white conversions using color temperature? As always, we’d love to see what you’ve been up to, so feel free to post your photos in the comments below!

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Adam Welch

Adam Welch is a full-time photomaker, author, adventurer, educator, and self-professed bacon addict. You can usually find him on some distant trail making photographs or at his computer writing about all the elegant madness that is photography. Follow his blog over at aphotographist.com and check out his brand new video eCourse on Adobe Lightroom Classic!