We’ve talked about how various colours convert to different shades of grey in earlier instalments of this article series. We’ve also talked about the importance of certain colours in greyscale and about the different components that make up colour – and thus grey – in the third part of the series.
In this part of the series, we’re going to take a look at something more subtle but nonetheless relevant. That’s white balance. Can the choice of white balance affect a conversion from colour to black & white? It definitely can. This is something that film shooters have known for years, that the colour of the light in the scene would have an impact on the effect of colour contrast filters used on the lens and rendered on the film. Intuitively it makes sense.
The image below was taken in the latter half of September shortly after 11:00 in the morning. Due to the time of year and the latitude I was at the light still has a bit of a warm tinge even at this time of day.
The White Balance in the camera was set on Auto and it did a pretty decent job of rendering the scene as I saw it. There was a slight warmth to the colour of the light.
Let’s look at what happens when we do a default conversion to black & white using the Black & White tool in Photoshop.
For a default conversion, this actually isn’t bad. There’s a pretty good separation of tones. The subtle shading in the clouds comes through from the colour version. The sky has been rendered a nice shade of grey.
For the sake of this article, I adjusted the White Balance of the original RAW file to show the differences. The next image is with the White Balance set to create a very warm colour cast to the scene.
Not really pretty but not completely unrealistic depending on the time of day one was shooting or if the WB had been set incorrectly in the camera. Nice thing about RAW is that a mistake in the WB can be corrected.
What happens when we convert it to black & white? The image below was converted, again, at the default settings of the Black & White tool in Photoshop.
The differences may not be evident immediately but there are differences. Most notably in the sky. The grey tone of the sky is different. Some of the subtle shading in the clouds is different and the reflection of the clounds in the swamp is different. Looking closely there are other, subtle differences as well. Overall contrast is a bit lower too.
Now let’s look in the other direction. The version below has the WB adjusted to the cool end of the pool.
This reminds me a bit of the very cool tones that could be rendered by some of the Fuji slide films. How’s it look in black & white?
Once again, subtle but noticeable differences and most evident in the same places. The shade of grey in the sky, the shading in the clouds, the reflection of the clouds on the water and overall contrast. There’s actually loss of a bit of shadow detail too.
The comparison image below shows all three side by side (original, warm, cool in that order) so that you can see the differences more clearly.
So while the differences may be subtle, there are differences nonetheless. And, as I mentioned earlier, intuitively this should make sense. We’re making various elements of the scene warmer or cooler in tone which will have an impact on how those warm/cool tones get translated to greyscale. What’s it mean for your b&w conversions? Maybe nothing. Maybe something. What it will mean is that the mix of colours used in creating the b&w version may have to be a bit different to achieve the desired grey tones and overall image contrast. Whether that’s important to you is something you have to decide for yourself. If you’re shooting RAW it less of an issue because you can adjust the WB before doing the conversion. If; however, you’re shooting JPEG, it will impact you more – particularly if you’re shooting black & white in camera. It also means that you can use White Balance creatively in black & white photography just as you can in colour photography.
You can see the effect of this in real time in a RAW editor like Adobe Camera RAW or Lightroom. If you select to convert the image to black & white then go back to the WB slider, moving the WB slider back and forth will show you the change in the image that results from the change in White Balance or colour temperature. The Tint adjustment in ACR or LR can also have a pretty significant impact on grey tonality and conversion to b&w. Try adjusting this between green and magenta to see the impact on the grey values.
How do you approach your black & white photography? Do you think about the White Balance when shooting? As always, feedback is most welcomed.
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