In this paper, a colour graphic document analysis is proposed with an application to ancient cadastral maps. The approach relies on the idea that images of document are fairly different than usual images, such as natural scenes or paintings... From this statement, we present an architecture for colour document understanding. It is based on two paradigms. Firstly, a dedicated colour representation named adapted colour space which aims to learn the image colour specificity and secondly a document oriented segmentation using a region growing algorithm supervised by a hierarchical strategy. Experiments are performed to judge the whole process and the first results show a good behaviour in term of information retrieval.