Convert PNG and GIF pictures to JPEG pictures with PHP

A lot of websites offer users to upload avatars, company logos or maybe just a picture that the user has taken. The most common picture formats are normally JPEG, PNG and GIF.

But how can you convert a GIF or PNG image from one of your website visitors into a JPEG image to store it on your webserver?

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Below is a short and easy guide to convert PNG and GIF images into the JPEG format with the help of PHP.

First, set a directory where the image should be stored and find out the file extension:

 //directory where your uploaded files are stored
 $uploads_directory = "/your/directory/where/you/want/to/save/your/images/"

//check extension of the file
 $str = $_FILES['file']['name'];
 $i = strrpos($str,".");
 if (!$i) { $BAD .= "An error occured."; }
 $l = strlen($str) - $i;
 $ext = substr($str,$i+1,$l);

//directory + file name of the image
 $upload_filename = $uploads_directory. "new_image.". $ext  ;

Then run the following code if the file extension is PNG or GIF:

//check file extension
 if ($ext == "png" || $ext == "gif"){

//new file name once the picture is converted
 $converted_filename = $uploads_directory. "new_converted_image.jpg";

if ($ext=="png") $new_pic = imagecreatefrompng($upload_filename);
 if ($ext=="gif") $new_pic = imagecreatefromgif($upload_filename);

// Create a new true color image with the same size
 $w = imagesx($new_pic);
 $h = imagesy($new_pic);
 $white = imagecreatetruecolor($w, $h);

// Fill the new image with white background
 $bg = imagecolorallocate($white, 255, 255, 255);
 imagefill($white, 0, 0, $bg);

// Copy original transparent image onto the new image
 imagecopy($white, $new_pic, 0, 0, 0, 0, $w, $h);

$new_pic = $white;

imagejpeg($new_pic, $converted_filename);
 imagedestroy($new_pic);

}

Let us know if you need any help implementing this feature on your website. One of our web developers will be happy to help you!