Adding schema itemprop image to the_post_thumbnail with filters

I have tried to apply filters to the_post_thumbnail() function using

apply_filters( 'post_thumbnail_html', $html, $post_id, $post_thumbnail_id, $size, $attr );

Here’s the code I have come up with but doesn’t seem to work completely

    function red_adjust_image_schema($html, $id, $caption, $title, $align, $url, $size, $alt) 
{
    $html="<div class="image-container" itemprop="image">". $html . '</div>';

    return $html;
}
add_filter('post_thumbnail_html', 'red_adjust_image_schema', 20, 8);

How can I add itemprop=”image” to the actual image element so it registers properly? Right now it seem like I can only do a container and wrap around $html?

Thanks

You’ve simply the wrong arguments (incl. the list of them).

$caption, $title, $align, $url, $alt

are too much in there.

And $attr is missing. Not that it matters how you name the vars (as long as they start with a character), but it’s easier to read for later readers.

function wpse76536_image_schema( $html, $post_id, $post_thumbnail_id, $size, $attr ) 
{
    return "<div class="image-container" itemprop='image'>{$html}</div>";
}
add_filter( 'post_thumbnail_html', 'wpse76536_image_schema', 10, 5 );