public function saveImage( $type = NULL )
	{
		if( !$this->source )
			throw new RuntimeException( 'No image loaded' );
		if( !$this->target )
			throw new RuntimeException( 'No modification applied' );
		if( !$this->targetUri )
			throw new RuntimeException( 'No target image URI set' );
		$type	= $type ? $type : $this->sourceInfo[2];
		switch( $type )
		{
			case IMAGETYPE_GIF:
				return imagegif( $this->target, $this->targetUri );
			case IMAGETYPE_JPEG:
				return imagejpeg( $this->target, $this->targetUri, $this->quality );
			case IMAGETYPE_PNG:
				return imagepng( $this->target, $this->targetUri );
			default:
				throw new Exception( 'Image Type "'.$type.'" is no supported' );
		}
	}