Yes I'm afraid copyright is being upheld on these pictures. Due not only to the expense but the time involved in creating these pictures then I'm afraid they cannot be allowed to be used freely. All unauthorised use will be challenged.

But all pictures available on the internet are free to use.

That just simply isn't true, copyright laws cover all media especially ones which can transmit pictures easily and display them to many people.

Can I not use the pictures at all?

Email me and ask. The pictures on the site are low quality web versions I will have a higher quality version tucked away on a hard drive somewhere.