In the General panel of the Layer Settings dialog box is an option to use an HSV modifier image. If this option is enabled, you can select an image to use as a filter that is applied to the layer. The selected HSV image is blended with the selected layer, resulting in a layer that has some interesting variety.
When the blend happens, the red channel on the HSV modifier image affects the hue of the layer, the green channel affects the saturation of the layer, and the blue channel in the image affects the luminosity of the layer. The effect is greatest when the red, green, and blue colors are near 0 or 255. Less effect happens when the image has a gray color with a value around 128.
The HSV modifier can be applied to any ...