How to Convert Photos to Black and White Using Image Calculations

Free Photoshop Actions and Lightroom Presets by MCP™

How to Convert Photos to Black and White Using Image Calculations

I’ve always loved the clean, crisp look of black and white magazine photos. But finding a conversion that recreated that look was a Goldilocks-esque challenge for me — this one is too muddy, that one is too gray, etc.

So I did a little happy dance when I discovered the Image Calculations tool in Photoshop. It’s a quick, easy way to create black-and-white images with just the right amount of contrast. This has become my go-to method for documentary images, from family snapshots to weddings to lifestyle sessions.

First, you need to start with a solid image. Good exposure and correct white balance are your best friends when using Image Calculations.

Image Calculations 01


Now go to Image > Calculations. Experiment with combining different channels — red, green, blue, or gray. Each combo will give you a slightly different look and highlight or darken different areas of your image.

Then choose your blending mode. Soft Light and Multiply tend to give the best results — Soft Light creates a bright, high-contrast black and white image, while Multiply will give you a moodier image with deep shadows.

For example, if I choose green/blue and set the blending mode to Soft Light…

Image Calculations 02


…this is what my conversion will look like.

Image Calculations 03


That’s a good start, but for this image, I was looking for an almost high-key vibe. So I tried red/green set to Soft Light instead…

Image Calculations 04


…and got this brighter conversion.

Image Calculations 05


I prefer this one because it makes her mischievous eyes and goofy glasses pop out as the immediate focus of the image. Of course, everyone edits differently, and the Image Calculations tool rocks because you can quickly tweak the image to fit your style.

Once you’ve found a combo you like, click “OK.”. Then go to Select > All, then Edit > Copy. Now go to your History panel and select the last step you did before you ran Image Calculations. In this case, it was just the initial “Open” command. Your image will revert back to color; go to Edit > Paste to paste the black-and-white conversion on top of your color version.

IMPORTANT: That may seem like a weird, unnecessary step — but don’t skip it! Even though you’ll see your image in black-and-white, it won’t save the changes you made using Calculations unless you copy and paste them. It also won’t save any of your edits, and actions won’t run properly, until you’ve done the copy-and-paste thing.

Now merge all the layers, and ta-da! You’re done.

Image Calculations 06


One quick tip — if you’re having trouble deciding which channels will work best with your image, go into the Channels window and click each color separately to see which channels have the details you want to keep (and which channels have the details you want to lose). For example, I can see that the red channel loses the detail in her cheeks but makes the glasses stand out — so I know that channel’s probably a keeper.

Image Calculations 07


There’s plenty of room for trial and error, and you only have to go back one step to start over if you don’t like the results — so have fun with it!

Image Calculations 08


Kara Wahlgren is a freelance writer and owner of Kiwi Photography in South Jersey, where she lives with her hubby and two awesome boy-toddlers. Check out her photography website or visit her Facebook page to see more of her work.


For quick, easy, one-click black and whites, check out MCP’s popular Fusion Photoshop actions, the Winter portion of Four Seasons actions, and Quick Clicks Lightroom presets.


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How to Convert Photos to Black and White Using Image Calculations