NDGradFilterCommand Class

ND filters are used by photographers to compress the dynamic range of high contrast scenes into a smaller range which can be better viewed or printed. These filters feature a 'dark' half and a clear half, with the transition either soft or hard depending on the effect desired. The dark half is typically either 2 or 3 "f-stops" darker. Multiple filters can be applied to achieve a greater or more complex effect.

A typical use for an ND filter is to darken the bright skies in an image to bring its tonal values more in line with those of the darker foreground. Sunrises, sunsets, horizon shots, canyons and other contrasty landscapes are good candidates for an ND filter.

The PhotoEffects ND Graduated is incredibly flexible, allowing you to adjust where in the image you want the effect applied (using the Location property), how dramatic you want the effect (using the Density parameter), how hard or soft you want the transition (using the Hardness property), how large an area you want the effect portion of the filter to cover (using the Radius property), and the angle at which you want the effect (using the Angle property). Angled effects are important if you have a diagonal sun/shade line or other non-horizontal dark/light division in your image.

The PhotoEffects ND filter can even provide "impossible" effects by allowing you to set the density of the "light" side of the filter. With traditional filters this is always transparent (a value of 1) but with the PhotoEffects filter you can set the starting density to be brighter or darker.