Understanding Black and White Filters in Lightroom

A Post By: Simon Ringsmuth

Shooting in black and white can be an amazingly creative way to explore new areas of photography, and help you see not only your pictures, but the world around you in a whole new light. However, unless you are shooting with black and white film or with a dedicated black and white camera like the Leica M Monochrom, all your pictures will initially be shot in color and later transformed into black and white through software tricks or filters.
Lightroom has an impressive array of presets that allow you to apply black and white effects to your color pictures, but in order to select the right filter for your particular pictures it’s important to understand how these presets work behind the scenes, and what they are really doing to your photos.

Back in the days of film photography, black and white film was composed of a single layer of silver crystals that were sensitive to light and affected the film in different ways depending on the wavelength, or color, of the incoming light. Green light (like reflected off of plants and trees) had a different effect on the film than red light (reflected off apples) or blue light (reflected off the sky).
When color film was invented it contained not one, but three layers of silver halide crystals, each of which produced different colors when exposed to light–similar to how the photosensitive pixels work on modern digital cameras. The problem with this method was that sometimes a photographer would need his or her film to be extra sensitive to different wavelengths of light, depending on the particular scene being photographed. One popular solution was to use colored filters that screwed onto the front of the camera lens, which still left the resulting image monochrome but changed its properties in significant ways.

A collection of color filters from Amazon that can be quite useful in black and white photography.

These filters operate by absorbing light on different parts of the spectrum while letting other colors pass through much more easily: green filters absorb more of most colors except green, blue blocks most colors except blue, and so on. This means that portions of the spectrum similar to the color of the filter will be lighter since more of that color of light makes it through the filter and essentially over-exposing those portions of the film. Conversely, portions on the opposite side of the color wheel from a given filter color will be darker since less of that light is allowed to pass through. For example, this diagram illustrates the basic principle behind a red color filter:

The fact that more red is allowed to enter through the camera lens means the camera’s light meter would then adjust itself accordingly: you’re essentially exposing for the reds, which means that a properly exposed black and white image with a red filter would have pleasing reds with very dark cyans, blues, and greens.

By taking this basic idea and applying it to modern digital photography you can start to see how different black and white post-processing solutions work. In Lightroom you can mimic the effects of a color filter when converting an image to black and white. It’s not quite the same as actually using a physical filter on your lens and shooting using black and white film, but it’s a decent approximation that gets the job done for most circumstances. The trick is knowing which filter to use in a given situation.
This shot of kids’ feet would be nice in black and white, but in order to choose the right style it’s important to know how each type of color filter will affect the results. A green filter will make the leaves lighter while darkening the skin colors, since they are somewhat opposite on the color wheel. A blue filter will lighten the bluish hue of the rocks and the darker areas in the leaves but darken the skin colors, though perhaps a bit too much.

Here’s what the same image looks like with five different Lightroom black and white filter presets applied:

In the end I chose a yellow filter to create the final image because it exposes the legs and feet a bit more while underexposing the blue and purple hues in the rocks:

Of course Lightroom is not actually putting a color filter over your picture, but using digital tricks to approximate the same effect. It does this by altering the values of various parameters in the Develop module when a given preset is applied. After selecting a Black and White Filter preset you can see how various color values change by choosing the B&W panel in the Develop module. Note how the sliders change for various selected Presets, such as the Yellow and Blue in the example below.

Lightroom is not applying different colors to a black and white image, but deciding how much of each color value to over or under-saturate in order to mimic the effect of putting the same type of physical filter on your camera. While it’s not quite the same as shooting in pure black and white, one of the nice advantages is how Lightroom allows you to essentially create custom black and white filters by adjusting the slider values yourself. You can tweak any of the existing Presets, not just the Black and White ones, by increasing or decreasing various sliders, and even save your adjustments as new Presets that you can apply instantly to any image.
As one more extreme example, here’s an image of some bocce balls with different filters applied.

The original color image, properly exposed.

Applying a red filter preset in Lightroom produces an image where the reds are properly exposed and a bit lighter, but the blue shirts are dramatically darker since red and blue are rather opposite on the color spectrum.

The same image with a Red black and white filter preset applied.

Now look what happens when a blue filter preset is applied. Just like a real physical filter on the front of the camera lens, the blues are lighter while all opposing colors are incredibly dark because very little of that light was allowed to pass through–or at least that’s the effect that Lightroom attempts to mimic.

A Blue filter preset now changes the image dramatically.

So how do you get a properly exposed image, with a well balanced amount of black and white across the frame? In real life you would use a green filter since this would block roughly equal amounts of both reds and blues, and the effect works quite well in Lightroom as well.

Using a green filter preset results in a well balanced image.

As you can see, getting a proper black and white conversion in Lightroom is not always as simple as just clicking a button. It helps to know not only what options are available, but why they function the way they do.
What about you? What are your favorite black and white tips and tricks in Lightroom? There is much more I have not covered in this article, and if you have anything you’d like to share leave your thoughts in the comments below.

Share this article.