Editing Unsharp masking (section)

=== Local contrast enhancement ===
Unsharp masking may also be used with a large radius and a small amount (such as 30–100 pixel radius and 5–20% amount<ref name="ciclce">[http://www.cambridgeincolour.com/techniques/local-contrast-enhancement.htm Local Contrast Enhancement], Cambridge in Color.</ref>), which yields increased local contrast, a technique termed ''local contrast enhancement''.<ref name="ciclce" /><ref>[http://www.luminous-landscape.com/tutorials/contrast-enhancement.shtml Understanding Local Contrast Enhancement], The Luminous Landscape.</ref> USM can increase either sharpness or (local) contrast because these are both forms of increasing differences between values, increasing slope—sharpness referring to very small-scale (high-frequency) differences, and contrast referring to larger-scale (low-frequency) differences. More powerful techniques for improving tonality are referred to as [[tone mapping]].