You can fill a region of an image with a reference image
            instead of a colour. The front, back, or result image can be used
            as the reference image. The Wash, Shade, Clone, or Reveal media
            can also be used to perform the fill.
         
         To
            fill a region with a reference image:
         
         
            - Click
               Fill.
               The Fill controls appear.
                
- Select
               the colour model and channels you want to work with.
            
- Set
               the range and softness in the Range and Softness fields.
            
- Select
               the Special Effects medium you want to use (Clone, Reveal, Wash,
               or Shade). See 
                        Using Special Effects Media.
            
- Set
               the Reference box to Front, Back, Result, or Saved, and set the
               brush opacity.
               A value of 100% fills the area completely with
                  the reference image.
                
- Enable
               Medium.
            
- Select
               a point in the area you want to fill.