If you're using 5.x-1 then there is what you do; go to "Administer>>Sit...

If you're using 5.x-1 then there is what you do; go to "Administer>>Site Building>> Themes " Right next to the title on the top of page there are two buttons "List" "Configure" click on configure, then right below it there would be a button labeled "Global Settings" click that. On this page you will find a group of check boxes with title "Display post information on", uncheck the contents types on which you don't want the post info to show up, in your case the Image check-box.

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