From its beginnings in the mid-12th century, the illustration of German-language manuscripts developed a strong tradition. It lasted well into the 16th century and continued in the age of print. The design and text-image arrangement of incunables (printed books before 1501) often show astounding similarities with the illustrated manuscripts of past centuries.
In the manuscripts, the arrangement of images and texts leads to various forms of interaction: Illustrations can explain and provide emphases to the texts, they can structure or decorate them.
The KdiH describes all manuscripts transmitting illustrated German texts dating from before ca. 1520. The KdiH also includes illustrated incunables and early printed books with illustrations that relate back to the manuscript tradition. All in all, the KdiH records about 2,500 manuscripts, organized in some 150 subject categories.
The KdiH examines relations between image and text and compares related manuscripts. Some manuscripts provide a continuous iconographic program indicating that the provision of both text and images was part of the basic concept. In the case of isolated images answers have to be found regarding their relationship to the text: Was the image intended or has it been added at a later date? Was its purpose to supplement or to comment on the text? Is it placed at the beginning of the text or near the episode describing the scene portrayed? Historiated initials are examined, as are gaps for images indicating that a manuscript was intended to be illustrated.