Alt Tags Not Displaying

I’ve tried to make modifications to the slick-front-end.php file to get the alt tags to display in the html.

$loop = new WP_Query($args);
$images = array();
$output = ”;
while ($loop->have_posts()) {
$loop->the_post();
$image = get_the_post_thumbnail(get_the_ID(), ‘full’);
if (!empty($image)) {
$post_id = get_the_ID();
$title = get_the_title();
$alt = get_post_meta($img_id , ‘_wp_attachment_image_alt’, true );
$content = get_the_excerpt();;
$image_src = wp_get_attachment_image_src(get_post_thumbnail_id(), ‘full’);
$image_src = $image_src[0];
$url = get_post_meta(get_the_ID(), ‘slickc_image_url’);
$url_openblank = get_post_meta(get_the_ID(), ‘slickc_image_url_openblank’);
$images[] = array(
‘post_id’ => $post_id,
‘title’ => $title,
‘alt’ => $alt,
‘content’ => $content,
‘image’ => $image,
‘img_src’ => $image_src,
‘url’ => esc_url($url[0]),
‘open_blank’ => $url_openblank[0],
);
}
}
return $images;

You can see where I have added the $alt function and then below that the ‘alt’ parameter in the array. And then for the display, further down in the code:

<?php echo $linkstart ?>
” title=”<?php echo esc_html($image[‘title’]) ?>” alt=”<?php echo $image[‘alt’] ?>” />
<?php echo $linkend ?>

The alt tag is there, but remains empty. Any suggestions on getting this to generate my alt tag for the image?