What are the best ways to take a black and white photo in today’s color digital world? That's a question I often get asked. And it's a great question because there is more than one way to convert a shot taken with a color camera into black and white. If you're not sure of the tricks, your images might not end up looking as good as they could.
Almost all digital camera makers today shoot all of your photos in color. There are black and white modes available, but they won't always work the way you'd like them to work to produce a snazzy photo.
De-Saturating for Black and White
The most popular way to create a black and white image from a color one is to 'de-saturate' the photo. There's usually a saturation slider on your paint program that you can move that removes all the color from the photo. In Photoshop, it's called Hue/Saturation. Set the Saturation to -100 and your image will become black and white.
Creating B&W Images through Saturation
It works, but it's usually not the best way to create a black and white image. Why not? Well, sometimes there is more of one color than another in an image (more blue sky, less red) and it's better sometimes to accentuate the parts of the image with that color, or the color difference between two colors. Take a look at the red top and blue jeans of the person in the above photo. In the black and white version, there is not a lot of difference between the shades of gray, so the image isn't as striking as the color one.
The better way is to use just color to make your image, or adjust the levels of each color separately. This allows us to fine-tune how much of the Red, Green and Blue colors that will appear in our final image.
Like in the color world, where colors can be slightly different depending on what white balance you set (and you can set the balance yourself to make the colors look how you want), the same is true when converting your image to black and white.
What desaturation does is give equal weight to the red, green and blue parts of your color image when converting to B&W. We can jazz our image up a bit by choosing just one color and creating a black and white from that.
Remember how the red top and blue jeans of our lovely model blended together when the image was desaturated? Look at what happens when we choose just one color channel when creating our B&W image.
Four different B&W images created using different methods
The red and blue channel images show her top and jeans being completely different shades of gray. That's because in the red channel, parts of the original image that were red (like her top) will be brighter, whereas other parts with no red (her jeans) will be darker. Parts of the image with all three colors (like her white cup) will be bright always.
Conversely, her blue jeans show as brighter in the blue channel image because that's what has most blue. The green channel shows similar dark colors for both pieces of clothing because neither have much green in them. See how they are much different than the desaturated image at the top?
By choosing only one color channel, we can show that she is wearing two different color items even in a black and white image.
Choosing just one channel can be done by opening the "Channel Mixer" in Photoshop and switching the slider for your preferred color to 100% and the other two to 0%. Make sure you also check the "Monochrome" checkbox to tell Photoshop that you want a black and white image.
I like the Red channel image the best. It shows a contrast between the colors of her clothing, and also between her jacket and the background leaves. The only thing I'd be concerned about would be her face. It could be seen as too bright.
There is no need to choose 100% and 0% on each of the colors. You can choose any combination of percentages you like. Using different numbers tells Photoshop to mix different amounts of each color channels to make the final photo. I sometimes use this by looking at each of the three channel images and ranking them from best to worst. Then setting the best color channel to 60%, the second best to 30% and the third best to 10%. Make sure they all add to 100%, otherwise your image may be darker or lighter than the original.
It doesn't work in all situations. It doesn't work that well on the girl above, but it does work wonders in any scenes with a blue sky. Choosing the blue channel at 60% will keep all the richness of a blue sky.
Handy Tip 1: Cameras use a filter array on the CCS which can mean one color has better detail than another color. In the common Bayer filter, the green channel will show the best detail because it has the most dots. If you find your black and white images are lacking detail, you can try choosing the green color (or add some of that channel into your final mix) to restore some detail.
Handy Tip 2: Once I’m finished with the channel mixer layer, I like to wrap it up by adding a contrast layer on top of everything. This helps to emphasize the different shapes in the photo. Play with this until you come up with something you like.
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