Image in Twitter cards not showing



I’m trying to make a twiter card to work with an summary_large_image type but unfortunatly, image is not showing.
I have checked the robots.txt, and the png (with pngcheck) but I can’t make it to work.
Can you please help me ?

Here’s the url:
Here’s the image:

The image is generated from a PHP script with imagepng() function.

Thank you a lot for your help!


Could find a solution from another post :

You need to add the Etag header in the header response like this :

header(‘Content-type: image/png’);
$image = ob_get_clean();
$etag = md5($image);
header(‘Last-Modified: ‘.gmdate(‘D, d M Y H:i:s’).’ GMT’);
header('Etag: '.$etag);


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