resize image แล้วคุณภาพของรูปลดลง แก้ยังไงก็ไม่หายค่ะ

$Pic_Dir = "BoardUploadPic"; 

	
	if(($_FILES["picupload"]["type"]=="image/jpg")||($_FILES["picupload"]["type"]=="image/jpeg")||($_FILES["picupload"]["type"]=="image/pjpeg")){
		$images_orig = ImageCreateFromJPEG($picupload);
		$pd=date("YmdHis");
		$newpicname ="$pd.jpg";
		
		}		
		else if($_FILES["picupload"]["type"]=="image/png"){
		$images_orig = ImageCreateFromPNG($picupload);
		$pd=date("YmdHis");
		$newpicname ="$pd.png";
		
    	} 
		else if($_FILES["picupload"]["type"]=="image/gif"){
		$images_orig = ImageCreateFromGIF($picupload);
		$pd=date("YmdHis");
		$newpicname ="$pd.gif";
		
    	} 
		
		else{		 
		echo "<script>alert('อัพโหลดได้เฉพาะไฟล์ .jpg / .png / .gif');history.back();</script>";
		exit();
	}

	$images = $picupload;
	$width=600; 	
	$size = getimagesize($images);
	if($size[0] <= 600)	{
	move_uploaded_file($_FILES["picupload"]["tmp_name"],"$Pic_Dir/$newpicname");
		} else if ($size[0] >= 600)	{
	
	$height=round($width*$size[1]/$size[0]); 
	$photoX = imagesx($images_orig);
	$photoY = imagesy($images_orig);
	$images_fin = imagecreatetruecolor($width, $height);
	imagecopyresampled($images_fin,  $images_orig, 0, 0, 0, 0, $width+1, $height+1, $photoX, $photoY); 
	imageJPEG($images_fin,"$Pic_Dir/".$newpicname,100);
	imagePNG($images_fin,"$Pic_Dir/".$newpicname,9);
	imageGIF($images_fin,"$Pic_Dir/".$newpicname,100);
	imagedestroy($images_orig);
	imagedestroy($images_fin);
	
		}