A method for identifying a distribution of maximal temperature, thereby determining a thermal history of a component, the method comprising the steps of: - applying a detection material on said component, the detection material being a temperature-indicating paint having a temperature-responsive colour and capable of indicating maximum temperatures, whereby each colour of the detection material is subject to a correspondent temperature; characterized by: - heating the component to known temperatures T i, such that the detection material acquires corresponding colours C i; - lighting the detection material using sequentially a plurality of different light sources each at two different emission intensities, each light source having a different emission spectrum; - detecting light reflected by the detection material through a digital monochrome camera; - defining first parameters of a first linear relationship between light intensity emitted by each light source and light intensity of light reflected by the detection material and detected by the digital monochrome camera; - lighting a reference source using sequentially the plurality of different light sources and the same lighting settings used for lighting the detection material; - detecting light reflected by the detection material through the digital monochrome camera; - defining second parameters of a second linear relationship between light intensity emitted by each light source and light intensity of light reflected by the reference surface and detected by the camera; - calculating a set of M non-dimensional parameters P i from the first parameters and the second parameters by ratio to the intensity of a reference colour (I' 0, I' ref0), the non-dimensional parameters P i being thereby independent from the measurement system used; - associating, through a measurement system, each colour C 1 to a respective one of the sets of M non-dimensional parameters P i; - establishing functional correlations T 1 = F (P1,..., P M) i between each temperature T i and said non-dimensional parameters P i correspondent thereto using an interpolation procedure; - heating the component to an unknown temperature T; - characterising the obtained colour C by a respective set of M non-dimensional parameters P 1,..., P M; - evaluating temperature T by means of said functional correlation T = F (P1,..., P M). - applying a detection material on said component, the detection material being a temperature-indicating paint having a temperature-responsive colour and capable of indicating maximum temperatures, whereby each colour of the detection material is subject to a correspondent temperature; - heating the component to known temperatures T i, such that the detection material acquires corresponding colours C i; - lighting the detection material using sequentially a plurality of different light sources each at two different emission intensities, each light source having a different emission spectrum; - detecting light reflected by the detection material through a digital monochrome camera; - defining first parameters of a first linear relationship between light intensity emitted by each light source and light intensity of light reflected by the detection material and detected by the digital monochrome camera; - lighting a reference source using sequentially the plurality of different light sources and the same lighting settings used for lighting the detection material; - detecting light reflected by the detection material through the digital monochrome camera; - defining second parameters of a second linear relationship between light intensity emitted by each light source and light intensity of light reflected by the reference surface and detected by the camera; - calculating a set of M non-dimensional parameters P i from the first parameters and the second parameters by ratio to the intensity of a reference colour (I' 0, I' ref0), the non-dimensional parameters P i being thereby independent from the measurement system used; - associating, through a measurement system, each colour C 1 to a respective one of the sets of M non-dimensional parameters P i; - establishing functional correlations T 1 = F (P1,..., P M) i between each temperature T i and said non-dimensional parameters P i correspondent thereto using an interpolation procedure; - heating the component to an unknown temperature T; - characterising the obtained colour C by a respective set of M non-dimensional parameters P 1,..., P M; - evaluating temperature T by means of said functional correlation T = F (P1,..., P M).