Infrared inspection allows the target to be analysed at wavelengths different from the visible wavelengths to reveal its substrates. Possible old drawings, sketches and drafts under the visible image can be seen with infrared imaging without damaging the original image.

Since the oil paint in the sample picture is transparent at SWIR wavelength, the pencil drawings on the lower layers are clearly visible in the infrared examination. In the sample picture, which we see as a colour picture with the naked eye, the boxes in the lower layer and the Micro-Design letters in the boxes can be seen when viewed at SWIR wavelength.