To achieve higher efficiency, turbomachinery components are often operated close to the thermal stress limits of the used materials. It is of great importance to have accurate knowledge of the temperature distribution across each part to ensure reliability and prevent material failure. Even small changes in temperature can significantly impact the service life. Therefore, precise measurement of temperature distribution on combustor and turbine components is crucial for the validation process of turbomachinery. This can be achieved using irreversible thermochromic paint. It reacts sensitively to temperature and time, altering its colour, structure and shine. To avoid disassembling the engine for post-Test component analysis, current research is enhancing the use of endoscopic imaging devices for diagnostics involving this thermochromic paint. However, challenges such as inconsistent illumination, limited resolution and failure to account for the paint s structure and shine can significantly increase measurement uncertainty. This paper develops a methodology to reduce the measurement error. Firstly, it evaluates the failures associated with endoscope measurements, concentrating on geometrical distortion, colour fidelity and colour constancy. To facilitate this, endoscope images are taken in a test rig with standardised specimens under controlled conditions. Secondly, a correction methodology is developed and validated within a high-pressure turbine module. The correction methodology comprises of an optimisation of the image acquisition process and application of image processing algorithms and techniques. The proposed approach intends to enhance the analysis of temperature-sensitive paint measurements through endoscopic imaging, thereby improving overall process efficiency and contributing to safer product development.