The photograph for the electronic identity document must be provided on paper (photographic paper!). However, there are different requirements for the photograph. For example, the image must be evenly illuminated and must not contain any shadows.
The exact specifications are shown in the sample photograph gallery (in German). If you have the picture be taken by a photographer, you should indicate to him or her that the image has to be suitable for a biometrical electronic ID document. Even in photo booths, help is often provided for creating a biometric compatible photo.
The passport authority official can use a sample passport photograph template as a reference and the aid of a computer program to determine whether the photograph meets the specifications or not.