The radiography of cultural property is the use of radiography to understand intrinsic details about objects. Most commonly this involves X-rays of paintings to reveal underdrawing, pentimenti alterations in the course of painting or by later restorers, and sometimes previous paintings on the support. Many pigments such as lead white show well in radiographs. has also been used to analyse the reactions of pigments in paintings. For example, in analysing colour degradation in the paintings of van Gogh.