add_filter( 'upload_mimes', 'valphoto_mime_types', 1, 1 ); function valphoto_mime_types( $mime_types ) { $mime_types['webp'] = 'image/webp'; // Adding .webp extension return $mime_types; } function webp_is_displayable($result, $path) { if ($result === false) { $displayable_image_types = array( IMAGETYPE_WEBP ); $info = @getimagesize( $path ); if (empty($info)) { $result = false; } elseif (!in_array($info[2], $displayable_image_types)) { $result = false; } else { $result = true; } } return $result; } add_filter('file_is_displayable_image', 'webp_is_displayable', 10, 2);