The great number and the size of many of the paintings at the Prado, as well as specific problems at the Pinacothèque, led the Cabinet of Technical Documentation of the Museum to adopt a new means of radiography. The general principles of the process are explained. The special assembling of the plates permits the creation of large-scale x-radiography with barely perceptible joinings. The automatic development of the plates noticeably improves the quality of the results. These procedures have resulted in improved radiographs of the Black Paintings of Goya. -- AATA