Converting Color to Black and White
It shouldn’t surprise you to learn that multiple methods are available for converting a color photo to black and white (which, as you know, is technically called grayscale). You can choose Image, Adjustments, Desaturate, or reduce the Saturation value to 0 in the Hue/Saturation dialog. Either of these ends up in the same place. Or, logically, you can convert the image to Grayscale mode (you’ll need to click OK when Photoshop asks if you’re really sure you want to discard all the image’s color data). This method gives you improved contrast over the Desaturate method. And there are other, more obscure techniques, involving converting an image to Lab Color mode and starting from the Lightness channel, or picking the best-looking of the red, green, and blue color channels.
All these conversion methods were rendered obsolete as of Photoshop CS3, when the Black & White command was introduced (choose Image, Adjustments, Black & White). Using a dialog crammed with sliders (see Figure 5.25), Black & White gives you the opportunity to take complete control over just how each of the colors in a color photo is converted to grayscale. You can even make adjustments directly in the image, as you can with the On-Canvas Adjustment tools in the Curves and Hue/Saturation dialogs. And if it’s too much bother to deal with all those sliders every time, you can take advantage of the comprehensive collection of presets Adobe has so thoughtfully included in the Black & White dialog.
Figure 5.25 You can take advantage of the Black & White dialog’s presets or create your own custom mix.
As with Levels and Curves, Black & White has an Auto button; click this to use Photoshop’s recommended settings for your image. The Auto function works better in Black & White than in the other dialogs in which it appears; it makes an excellent starting point for your own adjustments. The provided presets tend to be rather extreme and are most useful for special effects such as simulating an infrared image.
Working with the Black & White dialog is easy. Just click and drag any of the color sliders to change how objects of that color are converted to gray. If a red T-shirt is too dark with the default settings, drag the Reds slider to the right to brighten it. Or, if you prefer, click the T-shirt in the image window and drag to the right for the same results. To undo your changes without leaving the dialog, you can Option-click (Mac) or Alt-click (Windows) the Cancel button to reset all of the color sliders. To reset just one slider, Option-click (Mac) or Alt-click (Windows) its color chip.