What potential pitfalls should be considered when combining text input from HTML forms with image creation in PHP?

One potential pitfall to consider when combining text input from HTML forms with image creation in PHP is the risk of injection attacks if user input is not properly sanitized. To mitigate this risk, it is important to validate and sanitize any user input before using it to create images. This can be done by using functions like htmlspecialchars() to escape special characters and prevent malicious code execution.

// Sanitize user input from HTML form
$user_input = htmlspecialchars($_POST['user_input']);

// Use sanitized input to create image
$image = imagecreate(200, 200);
$black = imagecolorallocate($image, 0, 0, 0);
$font = 'arial.ttf';
imagettftext($image, 20, 0, 10, 50, $black, $font, $user_input);

// Output image
header('Content-type: image/png');
imagepng($image);
imagedestroy($image);