An <img src /> tag for an image attachment, scaling it down if requested.
The filter 'get_image_tag_class' allows for changing the class name for the image without having to use regular expressions on the HTML content. The parameters are: what WordPress will use for the class, the Attachment ID, image align value, and the size the image should be.
The second filter 'get_image_tag' has the HTML content, which can then be further manipulated by a plugin to change all attribute values and even HTML content.
<?php get_image_tag( $id, $alt, $title, $align, $size ); ?>
get_image_tag() is located in