The False Colour Infrared (FCIR) is based on the different response of materials in infrared radiation and combines visible RGB colour and infrared imaging. It has been used for materials differentiation and characterization, especially for painted works of art and pigments research. Visible, infrared and FCIR images of historical pigments, constructed using the traditional egg-tempera technique, demonstrate the different levels of transparency in IR radiation and the variety of pseudo-colours produced from FCIR . The latter reaffirms the results of previous FCIR studies in pigment identification. The blue and green colours appear reddish or grey in case of azurite. Yellow colours in FCIR derived from red-orange pigments. Among them, vermillion produces the brighter, most impressive yellow tones. Dark yellow brownish colours result in pale green, while lemon yellow turn to white. Umber and raw sienna remains brown, even if it acquires a brighter tone.
We are exloring the FCIR-RTI’s potential for the development of a new diagnostic methodology. In that way the RTI visualization would encapsulate, apart from the information related to shape, geometry and colour usually found in visible RTI, and the hidden details beneath the visible of IR-RTI, an initial indication about the chemical composition of the object under examination.