This filter works on grayscale images containing a single layer. The layer is used as selection mask and will work as stencil for the carving effect. The image to be carved (the target image) must be an RGB color or grayscale image, also with a single layer. This image should have the same size as the source image.
Here you may select the target image, i.e. the image the carving effect is applied to. The drop-down list will show you a list of opened images which may be carved.
If checked (default), the source image is used as stencil as described above. If unchecked, the inverted source image is used as stencil, e.g.:
In the example below, the target is a plain light yellow image. Note that, when Carve white areas is enabled (left image), the rectangular area is not carved, since it corresponds to a black area of the stencil. If this option is disabled (right image), the elliptical area, corresponding to the black area of the inverted stencil, is unchanged.