Image Sheduling

Hi All,
I am after some code or a plugin to do the following thing:
I need to have a single image URL to give to the JW Player on my site but need the image to be different based on the time of day the URL is loaded, for example: http://sitename.com/image1.jpg to be static but the actual image needs to be different based on a schedule, so for example, 3PM-6PM on Monday an image of a tree needs to be on that URL and from 6PM-9PM a picture of a dog. I need to automate this process similar to how images change themselves on the BBC iPlayer depending on the time/date combination.
Is this possible, if so, how? Even if the solution is to make this happen on the page itself (i.e. not static for the JW Player) that would be fine, just anything to make this appear in a post.
Many Thanks in advance.