The color-temperature response of the surface coated with a liquid crystal sheet or painted with slurry should be known prior to its use for temperature measurement. This step, called calibration is carried out to develop the intrinsic color-temperature response of the liquid crystals. During calibration, the color image of the LCs is acquired when the surface is held at a known, spatially uniform and steady temperature. The calibration effort can be either successively isothermal or a gradient technique .

Successive isotherm method

In the successive isothermal method, a temperature controlled test surface and the imaging system are used to generate liquid crystal color-to-temperature calibration data. The color image of the test surface is acquired after bringing the test surface and the liquid crystal to its event temperature. An average color value is computed and stored along with the temperature of the test surface. This process is repeated at subsequently higher temperatures until the clearing point temperature is reached. Though it appears to be simple, the successive isotherm method can be very time consuming since the amount of data is large and the processing requirement is acute.