Upload and resize images with PHP

Now this is a fairly common request on the net so I thought I put in my two pence and showcase how I upload and resize images... Below is my class that handles all my uploading and resizing functionality:

<?php
class Uploader
{
	public $Filename;
	public $Filename_temp;
	public $Filename_cleaned;
	public $Directory;
	public $Extension;
	private $__Allowed_extensions_array = array("jpg", "png", "gif", "doc", "docx", "pdf", "flv", "mp4", "mov");

	public function __construct()
	{
		$this--->Filename = null;
		$this->Filename_temp = null;
		$this->Filename_cleaned = null;
		$this->Directory = null;
		$this->Extension = null;
	}

	public function Upload()
	{
		//get information about this file
		$file_info_array = pathinfo($this->Filename);
		$this->Extension = strtolower($file_info_array['extension']); 

		//extension has been found in database, so its not a dodgy file
		if($this->Is_extension_allowed($this->Extension))
		{
			if($this->Filename != "")
			{
				//add the filename to the start of it
				//remove the extension and clean the filename
				$this->Filename_cleaned = $file_info_array['filename'];
				$this->Filename_cleaned = strtolower(str_replace(" ", "-", $this->Filename_cleaned));
				$this->Filename_cleaned = strtolower(str_replace("_", "-", $this->Filename_cleaned));
				$this->Filename_cleaned = strtolower(str_replace("'", "", $this->Filename_cleaned)); 

				// Create a unique file name
				$this->Filename_cleaned = $this->Filename_cleaned."-".date("s")."." . $this->Extension; 

				if (!copy($this->Filename_temp, $this->Directory.$this->Filename_cleaned)) 
				{
				return array("error_code" => 500, "error_message" => "Failed to copy file: ". $this->Filename_temp." - ".$this->Directory.$this->Filename_cleaned);
				}

				unlink($this->Filename_temp);	
				//send out an array with the relevent details
				$file_array = array("filename" => $this->Filename_cleaned, "ext" => $this->Extension, "filename_without_extension" => $this->Get_file_without_extension($this->Filename_cleaned), "error_code" => 200);	return $file_array;
			}
			else
			{
				return array("error_code" => 500, "error_message" => "File was empty");
			}
		}
		else
		{
			return array("error_code" => 500, "error_message" => "Invalid extension");
		}
	}

	public function Is_extension_allowed($ext = null)
	{
		//is the given extension allowed
		if(in_array($ext, $this->__Allowed_extensions_array))
		{
			return true;
		}
		else
		{
			return false;
		}
	}

	public function Get_file_extension($filename = null) 
	{
		//get information about this file
		$file_info_array = pathinfo($filename);
		$this->Extension = $file_info_array['extension'];
		return strtolower($this->Extension);
	}

	public function Get_file_without_extension($filename = null) 
	{
		//get information about this file
		$file_info_array = pathinfo($filename);
		return $file_info_array['filename'];
	}

	public function Get_readable_filesize($size = 0)
	{
		/*
		Returns a human readable size
		*/
		$i=0;
		$iec = array("B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB");
		while (($size/1024)>1) {
			$size=$size/1024;
			$i++;
		}
		return substr($size, 0, strpos($size,'.')+4).$iec[$i];
	}

	public function Resize_image($width = 0, $height = 0, $quality = 90, $filename_in = null, $filename_out = null)
	{
		$this->Filename = $filename_in;
		$this->Extension = strtolower($this->Get_file_extension($this->Filename));
		$size = getimagesize($this->Filename);
		$ratio = $size[0] / $size[1];
		if ($ratio >= 1){
		$scale = $width / $size[0];
		} else {
		$scale = $height / $size[1];
		}

		// make sure its not smaller to begin with!
		if ($width >= $size[0] && $height >= $size[1]){
		$scale = 1;
		}

		//height is not required and can be based by width only
		if($height == 0)
		{
		$scale = $width / $size[0];
		}	

		//width is not required and can be based by height only
		if($width == 0)
		{
		$scale = $height / $size[1];
		}

		// echo $fileext;
		switch ($this->Extension)
		{
			case "jpg":
				$im_in = imagecreatefromjpeg($this->Filename);
				$im_out = imagecreatetruecolor($size[0] * $scale, $size[1] * $scale);
				imagecopyresampled($im_out, $im_in, 0, 0, 0, 0, $size[0] * $scale, $size[1] * $scale, $size[0], $size[1]);
				imagejpeg($im_out, $filename_out, $quality);
			break;
			case "gif":
				$im_in = imagecreatefromgif($this->Filename);
				$im_out = imagecreatetruecolor($size[0] * $scale, $size[1] * $scale);
				imagecopyresampled($im_out, $im_in, 0, 0, 0, 0, $size[0] * $scale, $size[1] * $scale, $size[0], $size[1]);
				imagegif($im_out, $filename_out, $quality);
			break;
			case "png":
				$im_in = imagecreatefrompng($this->Filename);
				$im_out = imagecreatetruecolor($size[0] * $scale, $size[1] * $scale);
				imagealphablending($im_in, true); // setting alpha blending on
				imagesavealpha($im_in, true); // save alphablending setting (important)
				imagecopyresampled($im_out, $im_in, 0, 0, 0, 0, $size[0] * $scale, $size[1] * $scale, $size[0], $size[1]);
				imagepng($im_out, $filename_out, 9);
			break;
		}
		imagedestroy($im_out);
		imagedestroy($im_in);
	}
}
?>

Once the form has been submitted, the below code takes care of the uploading and resizing:

<?php
$u = new Uploader;
$u--->Directory = PATH_TO_FOLDER; //this needs to be updated and the define variable should be found in the config.php file

//upload the file
$u->Filename = $_FILES['FORM_ELEMENT']['name'];
$u->Filename_temp = $_FILES['FORM_ELEMENT']['tmp_name'];
$file_array = $u->Upload();
if(is_array($file_array) && ($file_array['error_code'] == 200))
{
	//if the upload was successful, resize the image to the dimensions required
	$profile_image = $file_array['filename'];
	$image_without_extension = $file_array['filename_without_extension'];
	$image_ext = $file_array['ext'];
	$u->Resize_image(256, 192, 90, $u->Directory.$profile_image, $u->Directory.$image_without_extension."-small.".$image_ext); //refer to the Resize_image function in Uploader class
}
?>