public static function checkRequirements($extension=null)
	{
		if(extension_loaded('imagick'))
		{
			$imagick=new Imagick();
			$imagickFormats=$imagick->queryFormats('PNG');
		}
		if(extension_loaded('gd'))
		{
			$gdInfo=gd_info();
		}
		if($extension===null)
		{
			if(isset($imagickFormats) && in_array('PNG',$imagickFormats))
				return true;
			if(isset($gdInfo) && $gdInfo['FreeType Support'])
				return true;
		}
		elseif($extension=='imagick' && isset($imagickFormats) && in_array('PNG',$imagickFormats))
			return true;
		elseif($extension=='gd' && isset($gdInfo) && $gdInfo['FreeType Support'])
			return true;
		return false;
	}