Glanzbilder are used in Poesiealbums. Poesiealbums are a form of autograph/friendship book. I had one as a child. It was white, with a kitten on the front cover. Poesiealbums were shared with your friends, relatives and teachers. They then would pen a favorite line of prose, poetry or quotation with a message to you, followed by a signature. Looking back I believe this is such an art form! When I presented mine to my elementary school American friends, I think they confused it a bit with a yearbook signature.
My German friends and family approached it differently. To them it was a place to mark how beautiful a person was to you - In a creative and literary manner, not a first person L.L.A.S note with a Ziggy drawing. I love how this album captured my personal dichotomy of growing up in two cultures. I love them both for different reasons. (For example, I wanted BOTH a bed with a German down comforter folded in half -like the German do - but also an American rainbow canopy bed set with matching bedskirt. Sadly, I could never marry the two forms of bedding effectively.)