Make uploader of image display as author

When I post something to our blog and embed an image, the image is of course clickable. However, when the new page with the image loads, it shows the WordPress user that was logged in instead of the author of the post, eg: May 25, 2012 by admin. How can I remove that annotation altogether?

Example:

http://manarin.com/2012/05/gas-tax-rates-by-state-as-you-prepare-for-your-memorial-day-weekend-road-trips/