Datasheet

Part I: The Basics of Color Editing

Suppose you took a picture in which the foreground subject is in the sun. In

the background, your eyes see a beautiful range of shaded trees. When you

print your photo, the leaves on the trees aren’t completely visible. They look

dark and don’t have much detail. The dark tones were clipped (cut off) from

the image.

Mixing Colors

Your computer monitor is capable of displaying a total of 16.7 million distinct

and individual colors. The monitor is capable of showing you all these colors

by mixing the primary hues of red, green, and blue together. Understanding

how your monitor mixes the colors ultimately helps you understand how to

edit your pictures for color correction.

Imagine a diaphragm similar to your camera’s diaphragm. You can turn the

f-stop ring to open or close the diaphragm. As you open the diaphragm, you

let more light pass through the lens. If you could close a diaphragm all the

way on a lens, you would block all light from passing through the lens.

When your monitor displays a color, it allows certain amounts of light to pass

through the RGB color phosphors in a similar fashion to a camera lens. The

monitor can control the amount of light that passes through the phosphors

in 256 individual steps. It’s like having a ring on your camera lens with 256

separate adjustments.

In computer terms, 0 (zero) is a number; therefore, the 256 value is really

measured from 0 (zero) to 255. If you assign 255 to the red hue and 0 (zero) to

the green and blue hues, you see a fully saturated red color on your monitor.

To test this theory, follow these steps:

1. Open any file in Standard Edit mode.

2. Double-click the mouse cursor on the Foreground color swatch in the

Tools palette.

The Color Picker dialog box opens.

3. Set the color to a fully saturated Red.

Type 255 in the R text box in the Color Picker. Type 0 (zero) in the G and

B text boxes, as shown in Figure 1-4. These numbers mean that you open

the diaphragm all the way for the Red channel and close it all the way

for the Green and Blue channels. The result is a fully saturated red color.

(For more on channels, see the section “Understanding channels,” later

in this chapter.)

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