You need to override the joomla content to create a effect for intro image or full article image.
The files located at joomla/templates/template_name/html/layouts/joomla/content/
Here you can customize full_image.php file or intro_image.php file
Example: if you want to implement the effect for image via category blog, you can customize the intro_image.php
For single article view, customize the full_image.php file.
