● Color Wheel: This picker is useful for exploring a wide range of colors. Pay attention to the brightness slider at the bottom, which changes the colors in the wheel above.
● Color Sliders: Use these sliders to specify particular grayscale brightnesses or RGB, CMYK, or HSB colors by number. You can also enter a hex color number directly. Or, you can find a color with another picker or the eyedropper tool and then look up its exact values here. Desktop publishers use this feature a lot, as do Web designers trying to determine hex colors. When matching colors with outside sources, click the gear button to choose the appropriate industry standard color palette before picking a color.
● Color Palettes: This picker shows color swatches from different custom palettes. Use the ••• button to make, add, rename, and delete palettes. (Find them in ~/Library/Colors.) The utility of these palettes is that you can share your own color collections, enabling coworkers to use identical colors easily, or you can download and import palettes for different uses, such as land-use categories for maps.
● Image Palettes: Click the ••• button here to load a new image, after which you can select any color in that image by clicking it. This picker could be useful for matching colors in a layout with those in a photo.
● Pencils: They used to be crayons, but then Apple got sophisticated. Or stopped licensing the names from Crayola.
Within each color picker, it’s usually obvious how to select different colors. Click the wheel, move the sliders, enter red-green-blue percentages, and so on. The selected color, which should be applied to the selection in your drawing or text, appears in the large square color well at the bottom left. If your selection doesn’t pick up the desired color, try dragging the color well in the lower section to a corresponding color box in your app.
Eyedropper
The Colors window offers another extremely useful way to select a color: the eyedropper. Find it in the bottom portion of the window, and click it to see a circular loupe that magnifies anything under it. Move the loupe until the single pixel in the middle is over the color you want, and then click. If you press the Space bar while the loupe is showing, the loupe displays the RGB values of that pixel.