Good evening to everyone

The concept is to make a web calendar in which the link (event) would be an image
The link in the calendar should be automatic made (diff colour) if the image (named date.png) exists in the server. So the point is to upload an image in my server and automatically in the calendar a link to this would be visible.
Is what am i asking for possible via PHP? If someone could give a hint i would be very greatful

Thanks