X-ray transmission radiography is a method widely used for investigation of inner structure of objects. Imaging detector records the changes in intensity of the X-ray beam induced by its attenuation in different parts of the sample. Using the unique large area pixel detector, we are able to achieve high spatial resolution at the level of micrometres as well as unlimited contrast in the measured radiograph. A common disadvantage of measurements with pixel detectors had been, until recently, their relatively small dimensions of a few cm2. This disadvantage has been recently successfully resolved by the development of a large area detector WidePIX10×10 composed of a 10 × 10 matrix of pixel Timepix detectors assembled with the so-called edgeless sensors. This large area detector is fully sensitive in an area of 14.3 × 14.3 cm and its matrix contains 2560 × 2560 pixels (6.5 million pixels). This contribution presents results of measurements of forgery of a Rococo Lady miniature, partial scan of the Karlov Mother of God painting, and a full-area measurement of two paintings, the Assumption of the Virgin Mary and the Transfiguration of Christ on the Mount from the property of the National Heritage Institute, Regional Office in Kroměříž, Vizovice Chateau. The radiography of the paintings with dimensions of 95 × 64 cm was carried out using scanning method performed in X-ray micro-radiographic laboratory of Centre of Excellence Telč (CET). The resulting radiographs with spatial resolution of 50 μm and dimensions of 18 400 × 12 000 pixels (220 million pixels) were used for the description of inner structure of the paintings besides other non-destructive research methods.