Thermography is concerned with the pictorial representation of infrared radiation emanating from an object. The instrument that produces visible images of this thermal radiation is called a thermograph, and the permanent recordings of these images are called thermograms. The thermograph may thus be characterized as being an electro-optical imaging device that operates as a wavelength converter, translating spatial and thermal information about an object to the visible spectrum from that of the infrared. In addition, special processing techniques may be employed to enhance or identify certain signal characteristics as an aid for the user in evaluating the displayed data.
J. M. Loftis,
I. L. Carwell,
"Metric Characteristics Of Thermography", Proc. SPIE 0026, Quantitative Imagery in the Biomedical Sciences I, (1 June 1971); doi: 10.1117/12.975346; https://doi.org/10.1117/12.975346