| Class | Description |
|---|---|
| PDFColorMask | Defines a color mask. A color mask specifies a range of colors to be masked out. |
| PDFImageMask | Defines an image mask. |
| PDFSoftMask | Defines a soft mask. A soft mask, also known as an alpha channel mask, uses a grayscale bitmap to define 256 transparency levels. |
| PDFStencilMask | Defines a stencil mask. A stencil mask uses a monochrome bitmap for specifying the image area that will be painted on the page. |