public ImageNullPixelMask preserveNulls(long nullValue,String compressionAlgorithm){
  this.imageNullPixelMask=new ImageNullPixelMask(getTileOperations().length,nullValue,compressionAlgorithm);
  for (  TileCompressionOperation tileOperation : getTileOperations()) {
    tileOperation.createImageNullPixelMask(getImageNullPixelMask());
  }
  return this.imageNullPixelMask;
}

public ImageNullPixelMask preserveNulls ( long nullValue , String compressionAlgorithm ) { this . imageNullPixelMask = new ImageNullPixelMask ( getTileOperations ( ) . length , nullValue , compressionAlgorithm ) ; for ( TileCompressionOperation tileOperation : getTileOperations ( ) ) { tileOperation . createImageNullPixelMask ( getImageNullPixelMask ( ) ) ; } return this . imageNullPixelMask ; }
preserve null values , where the value representing null is specified as a parameter . this parameter is ignored for floating point values where nan is used as null value .
