If an image covers the entire slide, where should I credit the author/licensor in a presentation? Let's pretend I want to use this image from Wikimedia Commons

Here's the license on the image:


  You are free:
  
  
  to share – to copy, distribute and transmit the work  
  to remix – to adapt the work
  
  
  Under the following conditions:
  
  
  attribution – You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).
  share alike – If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.
  


If the image is going to cover the entire slide on my Powerpoint presentation, where should I attribute the author/licensor? Can I have a slide in the end with all the attributions or should I mention it on the image itself (e.g. at the bottom right corner).

Edit: The presentation will be recorded and posted on YouTube.
Bottom right corner (maybe unobtrusive in gray, as not to interfere with the white background) seems right to me - you see this often in paper magazines, too. This way nobody can easily or accidentally strip the attribution. A [number] (even maybe just the slide number) and picture credits on the last slide would be the second-best choice.

And it's nice (for a change) to have someone respecting the license terms. Thank you :)