Converting color images to black and white

The simplest way to convert a color image to black and white is to desaturate the color or change the mode to grayscale. However, this method frequently produces inadequate results, because in doing so, you give up control of how different colors produce a given grayscale value.

For the best B&W photo conversion, use color controls

Black and white comparison

Click for larger view

The example shows the same image converted directly to grayscale (left) and converted using color controls (right).

The direct-to-grayscale conversion is visually flat while the color-controlled image shows a richer range of tones.

Here are two ways in which you can use your image editing program’s color controls to your advantage when producing black and white conversions.

Going through channels

The channel mixer tool allows control over how much each of the three color channels (red, blue and green) contribute to the photograph’s final grayscale tones. It’s the most powerful method, but the most challenging to master.

Channel mixerIn Photoshop, open the tool by clicking Image > Adjustments > Channel Mixer. Other editing programs (and versions of Photoshop) may have a similar tool, and menu locations may vary.

Click on the lower left tick box entitled “Monochrome” for black and white conversion. To get a feel for how each color channel affects the image, set each channel individually to 100%.

You may then adjust each of the red, green and blue sliders until you produce an image to your liking. You can even play with negative number values in various channels to create even more pronounced effects.

Do the hue

An alternative method is to create adjustment layers with Hue and Saturation controls. It takes a bit more time to set up, but allows for a high degree of control just by dragging one slider.

Hue/saturationWith the color image open in Photoshop, create two separate Hue/Saturation adjustment layers: Layers > New Adjustment layer > Hue/Saturation. Set the blending mode of the top layer to “Color” and move the Saturation slider to -100%.

On the bottom adjustment layer, move the Hue slider to apply an entire range of color filters to your image. This is your main control for using this technique. Once you’ve arrived at a look that you like, flatten the image and save.

Note: not all image editing programs, such as Photoshop Elements, support color channels. You can use the Hue and Saturation method, but it’s more complicated because programs like this do not allow you to adjust the Hue settings once the adjustment layer is in place — you have to adjust the Hue before creating the layer, which takes a lot of guesswork.

If you’re not familiar with using color filters in B/W, it can be hit or miss, so you may simply have to desaturate your image.

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