PLEASE DON'T VOTE ON THIS IMAGE. It is here only to support the article Using the Graduated Density (GD) Filter to Control Lighting in Outdoor Photography. Reverse Graduated Neutral Density (GND) filters provide a means to control lighting during photography when the line above the horizon is light, but the foreground and sky are relatively bright. Notice how it gets lighter towards the top (a normal graduated density filter would get darker towards the top). For more info, please refer to the article linked above.