upload multiple images and resize

I’ve written PHP code to upload multiple images to a server.

This function processes a maximum of 10 images at one time and if any image’s width or height is larger than 2000px it will resize it. But the code is a little bit slow.

I would like to hear your opinion of this code.

Is there a way to make it faster and more and secure?

P.S.: I use an .htaccess file in upload folder to make it more secure.

This is my PHP code:

$img_num=count($_FILES['upload_images']['name']);
if($img_num>0 && $img_num<11){

for($i=0;$i<$img_num;$i++){
if($_FILES['upload_images']['name'][$i]!=''){
$ext=explode(".",$_FILES['upload_images']['name'][$i]);
$ext=strtolower($ext[1]);

if ((($_FILES['upload_images']['type'][$i] == "image/gif")
|| ($_FILES['upload_images']['type'][$i] == "image/jpeg")
|| ($_FILES['upload_images']['type'][$i] == "image/jpg")
|| ($_FILES['upload_images']['type'][$i] == "image/pjpeg")
|| ($_FILES['upload_images']['type'][$i] == "image/x-png")
|| ($_FILES['upload_images']['type'][$i] == "image/png"))
&& ($_FILES['upload_images']['size'][$i] < 12000000)
&& in_array($ext,array("gif","jpeg","jpg","png"))){

$is_jpg=1;$ex='jpg';

switch ($ext){
case 'jpg':$image=imagecreatefromjpeg($_FILES['upload_images']['tmp_name'][$i]);break;
case 'jpeg':$image=imagecreatefromjpeg($_FILES['upload_images']['tmp_name'][$i]);break;
case 'png':$image=imagecreatefrompng($_FILES['upload_images']['tmp_name'][$i]);if($_FILES['upload_images']['size'][$i] < 2000000){$ex='png';$is_jpg=2;}break;
case 'gif':$image=imagecreatefromgif($_FILES['upload_images']['tmp_name'][$i]);$ex='gif';$is_jpg=3;break;
default:$image=imagecreatefromjpeg($_FILES['upload_images']['tmp_name'][$i]);break;
}

$path='upload/img_'.mb_substr(md5($_FILES['upload_images']['name'][$i].rand(0,50)),0,rand(5,10)).'.'.$ex;

$width=imagesx($image);$height=imagesy($image);
$resize=false;
if($width>2000 || $height>2000){
$width_orig=$width;$height_orig=$height;
$width=2000;$height=2000;
$ratio_orig=$width_orig/$height_orig;
($width/$height > $ratio_orig)?$width=$height*$ratio_orig:$height=$width/$ratio_orig;
$resize=true;
}


if($is_jpg==1){
if($resize){
$bg=imagecreatetruecolor($width, $height);
imagecopyresampled($bg, $image, 0, 0, 0, 0,$width, $height,$width_orig, $height_orig);   
imagejpeg($bg,$path,75);
imagedestroy($bg);
}
else{imagejpeg($image,$path,80);}
imagedestroy($image);
$img_url[]=$ex;
}


elseif($is_jpg==2){
$bg = imagecreatetruecolor($width, $height);
imagesavealpha($bg, TRUE);
imagefill($bg, 0, 0, imagecolorallocatealpha($bg, 0, 0, 0,127));
$resize?imagecopyresampled($bg, $image, 0, 0, 0, 0,$width, $height,$width_orig, $height_orig):imagecopy($bg, $image, 0, 0, 0, 0,$width, $height);
imagedestroy($image);
imagepng($bg,$path,8);
imagedestroy($bg);
}

elseif($is_jpg==3){
move_uploaded_file($_FILES['upload_images']['tmp_name'][$i], $path);
}

}
}
}

}

and this the .htaccess file:

IndexIgnore *

deny from all
<Files ~ "^(.*)+.(gif|jpg|png|jpeg|svg|mp4)$">
order deny,allow
allow from all
</Files>

Options -Indexes -ExecCGI
RemoveHandler .php .phtml .php3
RemoveType .php .phtml .php3
php_flag engine off 

ForceType application/octet-stream
<FilesMatch "(?i).jpe?g$">
    ForceType image/jpeg
</FilesMatch>
<FilesMatch "(?i).gif$">
    ForceType image/gif
</FilesMatch>
<FilesMatch "(?i).png$">
    ForceType image/png
</FilesMatch>
<FilesMatch "(?i).mp4$">
    ForceType video/mp4
</FilesMatch>