Photoshop CC: The Missing Manual

Meet the Color Channels

Understanding what you’re seeing in each channel gives you the know-how to create complicated selections and fine-tune your images. In this section, you’ll look inside the different color channels, beginning with the most common color mode: RGB.

Note

This section doesn’t cover alpha channels; they’re so important, they get their very own section that begins on The Mighty Alpha Channel.

RGB Channels

Unless you’re preparing an image that’s headed for a commercial printing press (as opposed to the inkjet printer you’ve probably got at home) and they require you to use CMYK, RGB mode is the place to be. After all, your monitor is RGB, as are your digital camera and scanner. But as the box on Why Are Channels Gray? explains, Photoshop doesn’t display individual channels in red, green, and blue—they’re in grayscale so you can easily see where the color is most saturated. Because colors in RGB mode are made from light (How Color Works), white indicates areas where the color is at full strength, black indicates areas where it’s weakest, and shades of gray represent everything in between (see Figure 6-3).

Tip

No matter which color mode you’re in, you can cycle through its various channels by pressing ⌘-3, 4, 5, and 6 (Ctrl+3, 4, 5, and 6 on a PC), though you’ll only use that last one if you’re in CMYK mode—which has four channels instead of three—or if you’re trying to activate an alpha channel in RGB mode. To go back to the composite channel so you can see the image in ...