Black and white photos
Mike Bedford reveals the secrets of good black and white photography, an art form that stands alongside its more colourful counterpart.
It’s an artform in its own right – this month Mike Bedford reveals the secrets of effective black and white photography.
Eastman Kodak introduced Kodachrome, the first mass market colour film, in 1935. Yet this didn’t relegate black and white photography to the history books. Take, for example, Ansel Adams, one of the best-known landscape photographers. He might have started his career before colour film became widely available, but his work continued into the 1970s and his most recognisable photos are black and white.
The artistic potential of this media isn’t lost on many modern-day photographers, who recognise its scope for dramatic effects. If you want a bit more evidence, you’ll find no shortage of landscape photo libraries offering black and white, while some such as www.davebutcher.co.uk specialise in monochrome exclusively. It’s not just landscape photographers who are drawn to this form of photography either. Wedding photographers often offer back and white as part of the mix, for example. At first sight, it might seem that photographing in monochrome is easy, and certainly no more challenging than working in colour. However, it’s an artform in its own right and you’re not going to get the best from this media without learning how to master it. Ultimately, the best way to become an expert is to have lots of practice and hone your skills over time.
If you’re inspired to try your hand at black and white photography, though, there are some key skills that you’ll need to acquire, and our aim here is to introduce you to these basic principles and techniques.
Straight from the camera
Most cameras are able to take black and white photos. However, using your camera’s built-in black and white mode isn’t a good idea, and the first important reason applies to any special effects that your camera might offer. The effect might look good in the viewfinder, but if you take just that single photo, you’ll only ever have the modified version of the shot. Specifically, you won’t be able to undo that effect if you subsequently decide you’d like to see the scene as you saw it with your eyes.
If, on the other hand, you take an ordinary photo, you can apply any effects you want later using photomanipulation software. So, to come back to our theme of black and white photography, if you choose that option in your camera, it’ll disregard all of the colour information – something that you won’t be able to restore in photo editing.
In the case of black and white photography, though, there’s a more technical reason for not using your camera’s built-in mode. We’ll look at this in a lot more detail later, but for now let’s just say that there’s no single way of converting a colour photo into black and white. Your camera will use a method that the manufacturer considered would provide acceptable results in most cases, but no one method will give the best results in all circumstances.
The bottom line, therefore, is that you should never use your camera’s built-in black and white mode. Instead, shoot in colour as usual, and convert the result to monochrome later, selecting one of the various methods we discuss in this article.
For the most part we’re going to be looking at how to process a colour image to create a good black and white one. However, it makes sense to think about what types of scene make good monochrome photos.
To start, it’s probably easier to come to a view about what doesn’t make a good black and white photograph. And while it might be obvious, a scene in which there’s little to differentiate parts of the image except for colour will make a poor monochrome photo. If you need to be convinced of this, take a look at the colour photo of pencils (below left) and the four black and white renditions. You’ll probably agree that, while the colour version is moderately attractive, you won’t choose to hang a print of any of the black and white versions on your living room wall.
This doesn’t mean that a brightly coloured subject wouldn’t be a good choice as a black and white photo – indeed it could well be – but that there should be more interest in the scene than colour alone. So, for example, a scene with lots of contrast – by which we mean one that contains a lot of difference between the darkest and lightest areas – is a classic example of a good subject for black and white.
Other things to look out for include interesting patterns and textures, but this is by no means an exhaustive list and you’ll learn from experience. Another way of learning is to spend time taking a critical look at the work of others. That doesn’t mean copying their work, but as a straightforward way of getting your creative juices flowing.
Basic methods
At this point we’re going to assume that you’ve got a selection of colour photos for converting to black and white. We’re going to be using GIMP, a highly respected photo-editing package that’s available under a variety of operating systems including Linux, although you should be able to use most fully featured alternatives. We used version 2.10.22, which is the latest stable version. Load your first colour photo into GIMP and we’ll try out a few ways of converting it to black and white.
An alternative to the familiar RGB colour model, in which any colour is defined by its percentage of red, green and blue light, is the HLS model, which stands for hue, lightness, saturation. Hue is the characteristic that’s most easily thought of as the basic colour, for example, red, orange, yellow, green, blue and purple. Lightness is fairly self-explanatory and ranges from zero per cent, which corresponds to black, through to 100 per cent, which is white. Finally, saturation is the strength of the colour in which 100 per cent represents a bright colour, while zero per cent represents shades of grey that will be defined solely by their lightness.
In the light of this explanation, it should be fairly obvious that one way of converting an image to black and white is to desaturate it or, in other words, to reduce the saturation to zero per cent. To do this, select Colors>saturation… and then, in the Saturation tool, gradually reduce the saturation while observing the result. You’ll notice that the colours become gradually fainter until the image eventually appears in just shades of grey which, of course, is what we mean by a black and white image.
Note also that, despite saturation commonly having values of zero to 100 per cent, the Saturation tool in
GIMP initially shows the saturation as one and, to desaturate it, you’ll have to alter it to zero. Save or export your desaturated photo under a different filename so you still have the coloured version with which you can try some other options.
Now we’ll use a very different way of converting your colour photo into a monochrome image or, to be more accurate, of creating three different black and white images. You’ll recall that we’ve already made reference to the RGB colour model and our next method extracts
the red, green and blue components of the image. Select Colors>components…>decompose and then, in the Decompose tool, ensure that RGB is selected as the Color Model and click OK. This will generate three layers, each containing just one of the primary colour components. Each of these are monochrome images because, individually, they contain no colour information, so they appear in shades of grey.
If the Layers Dialog is displayed (and if it isn’t go to Windows>dockable Dialogs) you’ll see thumbnails of the three layers in that dialog. All are visible, as shown by the Visibility icon (the “eye”) against them, although the large image will only show the top layer (red) because it’s fully opaque and it’s the top-most layer. However, you can view either of the other two layers by dragging them to the top of the list of layers.
When each of the layers is the topmost one, export the image so you’ll then have an easy way of comparing the original colour version with these three monochrome images. You’ll notice that they’re all very different and it isn’t difficult to figure out the reasons for the differences. For example, the colour of the red pencil has very little blue content so, in the blue component black and white image, the red pencil is pretty much black. Similarly, the blue pencils have a very high blue component so they look almost white or light grey in the blue component black and white image.
The red component and green component monochrome images also show dramatic differences between different colours while, in the case of the desaturated image we generated earlier, the differences between the pencils are much less stark. Some photoediting packages, but not GIMP, also have a dedicated “convert to black and white” function, which will sometimes produce a different result from the methods we’ve already seen. However, it’s not always clear exactly how this function works so, just like the automatic conversion within the camera, it’s probably better not to use any such mode.
We’ve seen several methods of black and white conversion, but it might not immediately be obvious which to use. That choice will differ from one photo to another and, what’s more, often none of the simple methods will be ideal so it might be necessary to use a different technique. We’ll look at this later, although such a method could often be thought of as a combination of the basic methods described earlier.
Despite suggesting that the basic methods often won’t produce good results, because it’s so simple, you might like to try desaturating as a first attempt, at least while you’re still learning the basics. In fact, now you’ve already witnessed the gradual reduction in saturation, there’s an easier way to achieve that, specifically Colors>desaturate>desaturate…>ok. In fact, this option offers rather more in the way of flexibility by offering several modes that you might like to try out. The most likely type of photo in which desaturation will work well is when there’s not much variety in colour and where you’ll be interested in shapes, patters or contrast. And before moving on, don’t forget that having done the basic black and white conversion, there’s still scope for improvement by further photo editing, for example increasing the contrast, a subject we’ll touch on later.
Working with camera film
As we move on, we could learn a lesson from black and white photographers of old. In the days of film and prior, there was no conversion to carry out because a black and white film would be used. But just like using a digital camera’s black and white mode, the film set a lot in stone by virtue of its characteristics – that is, its sensitivity to different colours.
However, photographers used coloured filters in front of the lens to reduce the amount of certain colours of light reaching the film. For landscape photography yellow, orange and red filters were often used, primarily to darken blue skies and, in so doing, increase the
contrast between the sky and clouds. Yellow filters produced a subtle effect and this increased progressively with orange and red filters, the latter being capable to creating a dramatic darkening of a deep blue sky. Splitting a colour image into its RGB components and choosing the red channel has a similar, but even more dramatic effect, and might be a bit of an overkill. However, there’s a way in which you get much more control over the process.
Having loaded a photo with a blue sky and clouds into GIMP, from the Colors menu, choose Components> Mono Mixer… to display the Mono Mixer tool. You’ll notice that the preview shows a monochrome image with, initially, the red, green and blue channels all set to 0.33, the result being the same as just desaturating.
Now, try reducing the amount of blue and you’ll notice that blue skies become increasingly dark. Depending on how much you reduce it, and the colours of other parts of the scene, this might result in the scene looking too dark, just as if it were underexposed. If so, you could try increasing the red and green components, but don’t go too far because this could cause parts of the image to be overexposed. Pay particular attenuation to the clouds, which is where overexposure might be especially notable, making them 100 per cent white and thereby losing the detail.
Final touches
The methods we’ve seen so far are the main ones, but there are others you could experiment with, even though you’ll probably find that they’re only of value in a minority of cases. For example, we’ve already used the Decompose tool to split a colour photo into its three primary colours, but you’ll notice that Color Models can be set to other values than RGB. Most of these will produce at least one black and white image, even though the other components of the decomposition will often look odd, to say the least. You’ll probably want to read up on these various colour models, to get a better idea of what you’re doing and understand why some components look better than others and why some bear no resemblance to a black and white photo.
To conclude, we’ll spend a bit of time looking at how you might improve your photo after you’ve done the initial conversion to black and white. To many people, high contrast is the essence of black and white photography, so increasing the contrast will be the most likely way you’ll want to improve it.
Having said that, common photo-editing techniques such as cropping, removing unwanted objects by cloning and noise reduction might also apply, but since they aren’t relevant to black and white photography, we’ll say nothing more about them here.
The simplest way of improving the contrast is to select Brightness-contrast… from the Colors menu and then, in the Adjust Brightness and Contrast tool, increase the contrast from its initial value of 0. This can be effective although you get a lot more control by using the Adjust Color Levels and the Adjust Color Curves tools that can be found under Levels… and Curves… in the Colors menu. Despite the reference to colour in both these tools, they’re no less applicable to photos you’ve already converted to black and white.
The Adjust Color Levels tool shows a graph of the brightness levels in the photo. It’ll often be a roughly bell-shaped curve although, if that curve is truncated at the left or right, the photo is over- or under-exposed. Even if the levels aren’t clipped at the ends, though, the bell curve might not occupy the full width from left to right, which means that the photo doesn’t contain the blackest of blacks or the whitest of whites. This often, but not always, less than ideal. To correct this, move one or both of the triangular sliders below the graph until they line up with the left and right edges of the curve.
Next, use the Adjust Color Curves tool to map new output levels to the input levels present in the image. Note the white line which is the key to altering the contrast, and which shows the mapping between input levels on the horizontal axis and output levels on the vertical axis. Initially, it’s a straight line passing though all points of equal input and output levels, so if you were to click OK then nothing would change. However, you can edit the curve by dragging points on it and alter the mapping. This can be used to produce some bizarre effects, but it can also improve contrast. The classic curve shape to achieve this starts with a short horizontal section at the bottom left, curves up to a diagonal straight line, and then curves down to another horizontal section at the top right. It can be loosely thought of as an S-shaped curve and boosts light shades and dark shades – practice makes perfect.
Whatever method you use to increase the contrast, though, be careful not to go too far because that will cause detail to be lost in the highlights and the shadows. In other words, make sure you don’t convert too many shades of dark grey into pure black and too many shades of light grey into pure white.