Converting images to WebP in PHP

convert.php

function convertToWebp(string $src, int $quality = 100): string
{
    $dir = pathinfo($src, PATHINFO_DIRNAME);
    $name = pathinfo($src, PATHINFO_FILENAME);
    $ext = pathinfo($src, PATHINFO_EXTENSION);

    $dest = "$dir/{$name}_$ext.webp";
    $is_alpha = false;

    switch (mime_content_type($src)) {
        case 'image/png':
            $img = imagecreatefrompng($src);
            $is_alpha = true;
            break;
        case 'image/jpeg':
            $img = imagecreatefromjpeg($src);
            break;

        default:
            return $src;
    }

    if ($is_alpha) {
        imagepalettetotruecolor($img);
        imagealphablending($img, true);
        imagesavealpha($img, true);
    }

    imagewebp($img, $dest, $quality);

    return $dest;
}