A few clients have expressed the wish to stop search engines from indexing image only pages on their sites. To do that would require a little html change in several system templates that link to those images. Remember these templates are system templates and you should follow the system template changes process explained here. Once you become accustomed to those steps these are the system templates that contain those "get_image.php" file links:

/system/classes/Image/display_thumbnail.tpl
/system/other/lightbox_slideshow.tpl
/system/listing_details/image_slideshow_link.tpl

Depends on the choice you have set here in the admin tool:

LISTING SETUP > FILE UPLOAD & DISPLAY SETTINGS > Image Block Layout

as to where else you need to change:

/system/listing_details/image_block/classic.tpl
/system/listing_details/image_block/filmstrip.tpl
/system/listing_details/image_block/gallery.tpl

The display choice in the above setting corresponds to one of the templates above.