public function markImage( $source, $target = NULL )
	{
		if( !$target )
			$target = $source;
		
		$creator	= new UI_Image_Creator();
		$creator->loadImage( $source );
		$image		= $creator->getResource();
		$type		= $creator->getType();

		$position		= $this->calculatePosition( $creator );
		$stampHeight	= $this->stamp->getHeight();
		$stampWidth		= $this->stamp->getWidth();
		$stampResource	= $this->stamp->getResource();
		imagecopymerge( $image, $stampResource, $position['x'], $position['y'], 0, 0, $stampWidth, $stampHeight, $this->alpha );

		$printer	= new UI_Image_Printer( $image );
		$printer->save( $target, $type );
	}