In last month’s article, I stated that most people convert color images to grayscale by, well, simply converting them to grayscale. The Image>Mode>Grayscale command suffices for most people. The effect of this method of conversion is to simulate the look and feel of the same subject photographed on Kodak Plus-X film. This may be fine for most people, but what about those of you who are looking for more?

Black-and-white photography has always been more challenging than color photography.

Black and white is a “purer” art form that cannot rely on the effect of color to enhance the image and impact the viewer. So, what if Plus-X doesn’t do it for you? What if you want to impart a different emotional feel to your image? What options do you have? Fortunately, plenty.

Converting to black and white

There are several procedures that you can use when converting from color to black and white. Some offer slightly more visual options than the simple mode conversion while others offer almost limitless variations and the opportunity to radically alter the visual impact of the resulting image.  Figure 1 shows our starting image, a sample file that comes with Adobe Photoshop. Figure 2 shows the result of the simple Image>Mode>Grayscale conversion, the result of which is a somewhat flat image, which lacks detail and separation in the leaves.

Fig. 1: Our original color image.	Fig. 2: The result of performing a simple mode conversion to grayscale.

Let’s explore some of the advanced grayscale conversion methods and see what they have to offer. It should be noted that although many of these techniques can be performed on CMYK images, it tends to be easier and can often yield better results if you convert the images to RGB first.

 

Pick a channel

Switch to the Channel panel and click on any of the channels. Do not click on the “eye” icon on the left of the channels but, rather, on the right-hand portion of the channel itself. Examine each channel to determine which one gives you the best-looking grayscale image. After you have examined each channel and chosen the one you like the best, click on that channel to select it (Figure 3).


Fig. 3: Using the Channels Panel, you
can examine and select the individual channels.

With the channel selected, click on Image>Mode>Grayscale. Click “yes” on the dialog box that will pop up asking you if you want to discard the other channels. You will select yes in this dialog box whenever it appears in any of the following techniques.  The result will be a grayscale image made up of data from that single channel (see Figure 4).

Fig. 4: The grayscale images produced by each individual channel.

The L* channel

The next method is a variation on the previous technique. First, convert the image into the L*a*b* space by clicking on Image>Mode>Lab Color. Next, in the channels panel, select the L or Lightness channel.

Click on Image>Mode>Grayscale, discard the other channels and you will be left with a grayscale image created using only the L* channel, the channel containing all the detail in the image.

Mix ‘em up

What if any of the individual channels don’t deliver the exact result you are looking for? Simple. Combine the channels. You can either select Image>Adjustments>Channel Mixer or add a Channel Mixer adjustment layer. In the Channel Mixer panel that pops up, click on the “Monochrome” box in the lower right-hand corner. Then, start moving the sliders to use a combination of the individual channels to generate the grayscale image (see Figure 5).


Fig. 5: By checking the Monochrome box in the Color Mixer,
you can use various percentages of your file to modify the results of the conversion.

While making the adjustments, don’t limit yourself to positive numbers. Move some of the sliders in the negative direction (see Figure 6) and continue to explore the variety available (see Figure 7). Once you have the look you want, select Image>Mode>Grayscale.


Fig. 6: Don’t forget that you can use negative values for the
sliders in the Channel Mixer.




Fig. 7: The results of the Channel Mixer
settings from Figure 6.

Full control ahead

For an almost limitless scope of possibilities, try this (see Figure 8). In the Layers panel, add a Hue/Saturation layer. Do not move any sliders in the panel that pops up; simply click on OK. Next, add a second Hue/Saturation layer but this time move the Saturation slider all the way to the left.


Fig. 8: Make sure you set the blending mode for the bottom adjustment layer to “color.” Double-click on the thumbnail to open the adjustment panel for the lower adjustment layer.

This will result in a fairly ugly grayscale conversion. Click on OK to close this panel. Select the lower Hue/Saturation layer and change its Blending Mode, located in the upper left-hand corner of the panel, to “Color.” Open the lower Hue/Saturation layer by double-clicking on its thumbnail. Finally, move the Hue slider left and right (see Figure 9) to modify the grayscale image.


Fig. 9: Adjust the sliders to obtain the desired look.

To fine-tune the conversion, select individual color families using the drop-down menu near the top of the panel (see Figure 10). Each color family can be further modified in this way, although the changes are subtle. Once again, select Image>Mode>Grayscale when you have the look you are after.


Fig. 10: From the Edit drop-down menu, select individual color families to further fine-tune the conversion.

Now go out and play

Keep in mind that no single technique works best for all images. The more of these techniques you have in your repertoire, the more adept you will be at optimizing grayscale conversions. Next time, we’ll explore a couple of methods you can use to speed up the above processes.

John Nate is a senior color specialist for Chromaticity Inc., an integrator of color technologies for the newspaper and other industries. He can be reached at 616.361.7773 or via e-mail at jnate@chromaticity.com.