There’s no denying the elegance of black-and-white photography. Simply by removing the distraction of color, you can sometimes better focus a viewer’s attention on a photo’s strengths. Most image editors make it easy to turn color photos into gray-scale images, but their default conversions don’t always end up creating the best pictures. For better results, you may need to try some exploratory surgery.
Shades of gray
While it’s possible to be objective about the accuracy of a color photograph—you can often go back and compare the photo with the subject—there’s no objective right or wrong when you’re creating a gray-scale image. That’s because your eye doesn’t automatically associate colors with specific shades of gray. This leaves plenty of room for creative control. When converting a color landscape, for example, you might choose to create a dark, foreboding sky, or a sky that’s very bright and unobtrusive.
iPhoto (part of the iLife ’06 suite, $79); Adobe Photoshop, and Adobe Photoshop Elements ($649 and $80, respectively) all offer multiple methods for converting color images to gray scale. By experimenting with these options, you can mine your photo for the most-pleasing contrast and the fullest range of shades. Bear in mind, though, that not all images look good in gray scale—some pictures work well because of their color.
Option 1: Use the default
All three programs offer an easy, one-click option for converting color images to gray scale. If you’re using Photoshop or Photoshop Elements, go to Image: Mode: Grayscale. If you’re using iPhoto 5 or an earlier version of the program, switch to edit mode, and then click on the B&W button in the editing toolbar. In iPhoto 6, switch to edit mode, open the Effects palette, and then click on the B&W button in the upper left corner of the palette. For more-dramatic results, follow the B&W effect with the Boost Color effect (click on the middle right tile), which will increase the contrast in your image and provide a very slight warming tint.
Option 2: Reduce saturation
Each program also includes a saturation slider, which lets you quickly eliminate color information. In iPhoto 5 or 6, open the Adjustments palette and drag the Luminance slider all the way to the left.
To do the same thing in Photoshop or Photoshop Elements, go to Layer: New Adjustment Layer: Hue/Saturation and click on OK. In the result-ing dialog box, drag the Saturation slider all the way to the left to create a gray-scale image. Because you’re using an Adjustment layer, you can always remove the layer later to restore your image to full color.
Option 3: Check your channels (Photoshop only)
A computer creates color images by combining separate red, green, and blue versions (called channels ) of the same image. In Photoshop, you can peruse these channels by opening the Channels palette. Each channel appears as a different gray-scale conversion. A red tile roof, for example, might appear very bright in the Red channel but very dark in the Blue channel.
If you like the gray-scale image in one of the channels, you can extract it into a regular document by opening the Options pop-up menu in the corner of the Channels palette and selecting Duplicate Channel. In the resulting dialog box, set the Destination: Document menu to New and then click on OK. The selected channel will appear in a new document. To turn your new single-channel document into a regular document, go to Image: Mode: Grayscale. (You can also turn it into an RGB document—if you want to add a sepia tone, for example.)
One Photo, Many Gray-Scale Variations Depending on how you convert the colors, a single photo can produce dramatically different gray-scale images. The left image is the result of switching to Grayscale mode. The center image is a single channel pasted into a new document. I created the third image by mixing individual channels in Photoshop CS2.
Option 4: Mix your own gray scale
If none of these options produces a gray-scale image quite to your taste, and if you’re willing to put in a little extra work, you can customize your conver-sion by tweaking the color channels that make up your image.
Using Photoshop In Photoshop, you can blend separate channels via the Channel Mixer (Image: Adjustments: Channel Mixer). In the Channel Mixer dialog box, select the Monochrome option to create a gray-scale image. Then move the separate Red, Green, and Blue sliders to specify how much of each channel you want to throw into the mix. You should feel free to experiment here; however, be sure to keep the total of all three sliders at 100 percent. Exceeding 100 percent will result in an overexposed image, while going lower will leave you with an underexposed image. Use the Constant slider to lighten or darken your image.
Using iPhoto iPhoto doesn’t offer access to separate color channels for whipping up your own gray-scale conversion. However, it is possible to tweak your gray-scale image from within the program, at least to some degree.
In iPhoto 6, select the B&W option from the Effects palette. Next, open the Adjust palette and try moving the Saturation, Temperature, and Tint sliders until you find a setting you like. Adjusting these sliders changes the underlying color values in your image. As you desaturate those colors, they can yield very different shades of gray.
Using Elements Similarly, Photoshop Elements doesn’t offer a Channel Mixer. However, there is a workaround. Follow the preceding instructions for desaturating the image using an Adjustment layer. When you’re done, go to the Layers palette, click on the layer containing your original image, and then go to Layer: New Adjustment Layer: Levels and click on OK. In the Levels dialog box, use the Channel menu to select and modify the individual Red, Blue, and Green channels to your liking.
Best of both worlds
A Splash of Color Using a simple layer-compositing technique, I converted the background of this image to gray scale, leaving the woman in the foreground in color.
Sometimes it can be nice to leave a color element or two in your black-and-white image. You can easily create this effect in Photoshop.
Step 1 Open your original color image and press Command-A to select all, and then press Command-C to copy it to the Clipboard.
Step 2 Use any of the methods described in this article to convert your color image to gray scale. If you use option 1 to switch to gray-scale mode, you’ll need to switch back to RGB mode before you can continue (choose Image: Mode: RGB). The image remains gray scale, but the document can now include color.
Step 3 Choose Edit: Paste (Command-V) to paste the original color image in a new layer over the gray-scale one.
Step 4 With the new layer selected in the Layers palette, choose Layer: Layer Mask: Reveal All to add a layer mask to your color image. Use the Brush tool to paint black paint into any areas where you don’t want color. The black paint in the layer mask will mask out those areas of the color layer, revealing the gray-scale image beneath. Remember that you can switch to white paint to reveal any color information you accidentally removed.
Contrast is the single most important element of a successful black-and-white photo. Once you’ve made the conversion to gray scale, use your image editor to play with the contrast. In Photoshop, Photoshop Elements, and iPhoto, the best way to adjust contrast is with the Levels control. Drag the black- and white-point controls toward the center to increase overall contrast. To brighten or darken the gray tones in your image, adjust the Levels middle slider (in Photoshop or Elements) or the Exposure slider (in iPhoto).
[ Ben Long is the author of Complete Digital Photography, third edition (Charles River Media, 2004). ]