Correcting Shadows

Shadows/Highlights

Tonal Width:

Radius:

Highlights

Tonal Width:

Radius:

The most important aspect of this dialog is the shadows, which shadows are adjusted according to three parameters: Amount:

► Amount r Tonal Width r Radius

Shadows/Highlights brightens individual pixels relative to their neighbors. The radius setting determines the size of the circle within which Photoshop adjusts neighboring pixels. The exact construction of the algorithm Adobe uses is a secret, but it is obvious that it always attempts to limit changes to discreet objects. For example, a dark-colored telephone cable will not necessarily be brightened just because the radius setting says that it happens to be near a section of bright blue sky.

The Tonal Width parameter determines which tonal values are considered to be shadows, while the Amount parameter determines the strength of the adjustment that is applied.

Start by setting Amount, followed by Tonal Width. You can then play with the Radius setting until you either get the result you are looking for or start again from the top. These settings are not as complex as they might appear at first. Start with our default settings shown in figure 4-29and see where you end up when conducting your own experiments.

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