public void setImageMask ( Image mask ) throws DocumentException { if ( this . mask ) throw new DocumentException ( "An image mask cannot contain another image mask." ) ; if ( ! mask . mask ) throw new DocumentException ( "The image mask is not a mask. Did you do makeMask()?" ) ; imageMask = mask ; smask = ( mask . bpc > 1 && mask . bpc <= 8 ) ; }
Sets the explicit masking .