Our team reviewed VAT regulations on sales of digital images in the EU and the European Community. From our research, we understand that this has been a debated but not resolved topic for the EU. Many European countries are working internally to decide on how to impose additional taxes on such products. At this time, we are not aware of any VAT that is imposed on digital images supplied over the internet.
You may want to consider reviewing the European Union COUNCIL DIRECTIVE 2006/112/EC that discusses in detail VAT for electronically supplied goods. It's not an easy read though.
Of course, there may be additional sales taxes (in addition to VAT) that are specific to Germany. We recommend you consult your local tax adviser for proper application of VAT/sales taxes in your circumstances.
Note that if you are required to charge additional sales tax, you can set it up in your Zenfolio account under SELLING> Sales Tax.