Convert Image Format In PHP (WEBP JPG PNG GIF)

Welcome to a tutorial on how to convert the image file format in PHP – From JPG to WEBP, from PNG to JPG, from PNG to WEBP, and whatever else.

That’s all, 3 lines of code. To convert the other file formats, simply open/save the image using their respective functions –

• imagecreatefromjpeg() imagejpeg()
• imagecreatefrompng() imagepng()
• imagecreatefromgif() imagegif()
• imagecreatefromwebp() imagewebp()
• imagecreatefrombmp() imagebmp()

That covers the basics, but read on for more examples!

 

 

TABLE OF CONTENTS

 

 

EXAMPLE CODE DOWNLOAD

Source code on GitHub Gist

Just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

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TUTORIAL VIDEO

 

1) CONVERT SINGLE IMAGE

<?php
// (A) IMAGE CONVERT FUNCTION
function imgcon ($from, $to, $quality=null) {
  // (A1) CHECK VALID IMAGE TYPE
  $extf = strtolower(pathinfo($from, PATHINFO_EXTENSION));
  $extt = strtolower(pathinfo($to, PATHINFO_EXTENSION));
  $valid = ["bmp", "jpg", "jpeg", "png", "gif", "webp"];
  if (!in_array($extf, $valid) || !in_array($extt, $valid)) { return false; }
 
  // (A2) PROCESS CONVERSION
  if ($extf=="jpg") { $extf = "jpeg"; }
  if ($extt=="jpg") { $extt = "jpeg"; }
  $fnf = "imagecreatefrom$extf";
  $fnt = "image$extt";
  $img = $fnf($from);
  imagepalettetotruecolor($img);
  if ($quality !== null) { $fnt($img, $to, $quality); } else { $fnt($img, $to); }
  imagedestroy($img);
  // unlink($from); // delete source image if you want
  return true;
}
 
// (B) GO!
echo imgcon("ONE.jpg", "DEMOA.webp") ? "OK" : "ERROR" ;

This simple function pretty much does the same thing as the introduction snippet. Except that it is much more convenient – It “detects” the extensions and automatically calls the respective imagecreatefromX() and imageY().

 

 

2) MASS CONVERT THE ENTIRE FOLDER

<?php
// (A) SETTINGS
$cdir = __DIR__ . DIRECTORY_SEPARATOR; // convert all images in this folder
$cto = "webp"; // convert to this format
$cqy = null; // convert quality, null to use default
 
// (B) CONVERT IMAGE FILES
$clist = array_diff(["bmp", "jpg", "jpeg", "png", "gif", "webp"], [$cto]);
$clist = "$cdir*.{" . implode(",", $clist) . "}";
foreach (glob($clist, GLOB_BRACE) as $file) {
  // (B1) "SAVE AS" FILE NAME
  $saveas = $cdir . pathinfo($file, PATHINFO_FILENAME) . ".$cto";
  if (file_exists($saveas)) { continue; } // do not overwrite
 
  // (B2) PROCESS CONVERSION
  $extf = strtolower(pathinfo($file, PATHINFO_EXTENSION));
  if ($extf=="jpg") { $extf = "jpeg"; }
  $extt = $cto=="jpg" ? "jpeg" : $cto ;
  $fnf = "imagecreatefrom$extf";
  $fnt = "image$extt";
  $img = $fnf($file);
  imagepalettetotruecolor($img);
  if ($cqy !== null) { $fnt($img, $saveas, $cqy); }
  else { $fnt($img, $saveas); }
  imagedestroy($img);
  // unlink($file); // delete source image if you want
  echo "$saveas - OK";
}

If you need to convert an entire folder, here is a snippet that will help.

• (A) Define the target folder and what image format you want.
• (B) We use glob() to fetch a list of all the images and loop through them.
• (B1 & B2) The same old “detect extension and convert automatically”.

 

 

3) UPLOAD & CONVERT

3A) HTML UPLOAD FORM

<form action="3b-upload-convert.php" enctype="multipart/form-data" method="post" target="_blank">
  <input type="file" name="up" required accept=".bmp,.jpg,.jpeg,.png,.gif,.webp">
  <input type="submit" value="Upload">
</form>

This is just a simple file upload form. If you want “fancy uploads”, I will leave a few links below.

 

3B) PHP CONVERT UPLOADED IMAGE FILE

<?php
// (A) SETTINGS
$cdir = __DIR__ . DIRECTORY_SEPARATOR . "test" . DIRECTORY_SEPARATOR; // save to this directory
$cto = "webp"; // convert to this format
$cqy = null; // convert quality, null to use default
 
// (B) CHECK UPLOADED FILE
$ext = strtolower(pathinfo($_FILES["up"]["name"], PATHINFO_EXTENSION));
if (!in_array($ext, ["bmp", "jpg", "jpeg", "png", "gif", "webp"])) { exit("INVALID IMAGE"); }
 
// (C) MOVE UPLOADED FILE
$saveto = $cdir . $_FILES["up"]["name"];
move_uploaded_file($_FILES["up"]["tmp_name"], $saveto);
 
// (D) CONVERT IF NEEDED
if ($ext != $cto) {
  $extf = $ext=="jpg" ? "jpeg" : $ext ;
  $extt = $cto=="jpg" ? "jpeg" : $cto ;
  $saveas = $cdir . pathinfo($saveto, PATHINFO_FILENAME) . ".$cto";
  $fnf = "imagecreatefrom$extf";
  $fnt = "image$extt";
  $img = $fnf($saveto);
  imagepalettetotruecolor($img);
  if ($cqy !== null) { $fnt($img, $saveas, $cqy); }
  else { $fnt($img, $saveas); }
  imagedestroy($img);
  // unlink($saveto); // delete source image if you want
}
 
// (E) WHAT'S NEXT?
// REDIRECT TO ANOTHER PAGE?
// SHOW AN "UPLOAD OK PAGE"?
// SIMPLE MESSAGE?
echo "OK";

Don’t be intimidated… We are pretty much doing the same old “open image and save” here, but only on the uploaded file.

1. Settings – Where to save the uploaded file and what format you need.
2. Check if the uploaded file is a valid image.
3. Save the source image.
4. Convert the image if required.
5. What to do after the upload/conversion.

 

 

 

COMPATIBILITY CHECKS

• Arrow Functions – CanIUse

Works on all modern “Grade A” browsers.

 

LINKS & REFERENCES

• GD Image Functions – Official PHP Manual
• Drag-and-Drop Upload – Code Boxx
• Large Files Upload In PHP (Resumable Upload) – Code Boxx
• PHP Resize Images – Code Boxx
• Javascript Upload Progress Bar – Code Boxx