convert_image_to_webp_in_php.php

<?php 

function convertToWebp($imagePath) {
	if(!file_exists($imagePath)) {
		return false;
	}

	$info = getimagesize($imagePath);
	$format = strtolower(substr($info['mime'], strpos($info['mime'], '/') + 1));
	
	$image = null;
	if ($format == 'jpeg') {
		$image = imagecreatefromjpeg($imagePath);
	} elseif ($format == 'png') {
		$image = imagecreatefrompng($imagePath);
	}
	
	if (!$image) {
		return false;
	}
	
	$webpImagePath = preg_replace('/\.(jpeg|jpg|png)$/', '.webp', $imagePath);
	
	return imagewebp($image, $webpImagePath);
}

convertToWebp(__DIR__ . '/img.jpg');
convertToWebp(__DIR__ . '/image.jpg');
convertToWebp(__DIR__ . '/image.png');