Color filters in Black and White Photography

Color filters in Black and White Photography are used to control the reproduction of colours in terms of greys.
White is the result of combining all colors of the visible spectrum, while black is the result of the absence of all of them.Primary colors that constitute white light are red, green and blue. These colors cannot be generated by the combination of other colors.

On the other hand, if you take out red, you’ll end up with cyan. If you take out green, you’ll end up with magenta. And if you take out blue, you’ll end up with yellow. This is why red, green and blue are called additive primaries. And cyan, magenta and yellow are called subtractive primaries.

From what you can see on the color wheel below, every 2 opposite colors are called complementary colors. If you use a filter of a specific color, you will darken (or emphasize) it’s complementary color on the wheel while lightening that same color.

For example, to darken the blue/cyan skies in your photograph you would use a yellow, orange or red color filter (with red having the strongest darkening effect). In the same way, to lighten skin tones in portrait photography you would use a red filter (skin tones mainly comprise of red tones). To lighten foliage and green grass, you would use a green filter. And so on…

Why are we talking about theory of Color filters in Black and White Photography?

Photographs consist of a range of varying combinations of the red, green and blue to produce varying image colors and tones. A black and white image is the reproduction of the varying tones of color, and is created from the manipulation of the original image colors. Every different approach to manipulating one color image would yield a different black and white result, and every good black and white photo only starts with a good color one.

Color filters in black and white photography

Using Color filters in Black and White Photography loaded film or an intended black and white final digital outcome affects very much the look and effect the final image would have. Color filters work by cutting on light of their complementary colors and passing light of their same color, thus the lightening effect of similar colors and the darkening effect of complementary colors. Remember though that this act of cutting light means less light making it through the lens and onto the digital sensor or photographic film, so longer exposure times might be needed to make up for light loss.

So this all makes sense now right? To give more punch to white clouds against a blue sky, you would use a yellow filter which would darken the sky a bit so the clouds would pop out a little. This is why, folks from the early days called yellow filters cloud filters. To darken the sky even more, you would use a red filter. And this is why film folks call the red filter the sky filter as well.
A blue filter would darken skin tone, since as I’ve mentioned earlier, skin tones mainly comprise of red. This can be incorporated in portrait, people and nude photography. And a so-called spring/summer filter (yellow to green filters) would lighten foliage, grass and yellow and green tree leaves.

Achieving color filter effects in the digital darkroom

Photo-editing software such as Adobe Photoshop enable you to apply different color filter effects to your black and white images, producing a result similar to the one you would get if you actually used a color filter at the time of exposure.