How can the PHP code be modified to ensure that the captcha image displays correctly on all systems and browsers?

The issue of the captcha image not displaying correctly on all systems and browsers can be solved by ensuring that the image is generated with the correct content type and headers. This can be achieved by setting the content type to image/png and sending appropriate headers before outputting the image data. 

<?php
// Start the session
session_start();

// Generate a random captcha code
$captcha_code = substr(md5(rand()), 0, 6);

// Store the captcha code in the session
$_SESSION['captcha_code'] = $captcha_code;

// Create a blank image with dimensions 120x30
$captcha_image = imagecreatetruecolor(120, 30);

// Set the background color to white
$bg_color = imagecolorallocate($captcha_image, 255, 255, 255);
imagefill($captcha_image, 0, 0, $bg_color);

// Set the text color to black
$text_color = imagecolorallocate($captcha_image, 0, 0, 0);

// Write the captcha code on the image
imagestring($captcha_image, 5, 10, 5, $captcha_code, $text_color);

// Set the content type and send appropriate headers
header('Content-type: image/png');
header('Cache-Control: no-store, no-cache, must-revalidate');
header('Cache-Control: post-check=0, pre-check=0');
header('Pragma: no-cache');

// Output the image
imagepng($captcha_image);

// Free up memory
imagedestroy($captcha_image);
?>

Keywords

PHP captcha image display cross-browser compatibility code modification

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