Combining the spectral information of dual-band images to enhance contrast and reveal details

A method to calculate an emissivity image out of two thermographic images taken at different wavelengths has been developed. Main part is a thermal pixel to pixel calibration to make measurements physically comparable. The new image shows enhanced contrast in several nondestructive testing situations and reveals details that could not be accessed in the input images. Examples for passive and active thermography are presented using an infrared dual-band camera working simultaneously in the MWIR and LWIR band. Reflection characteristics of CFRP and its components apparent in thermography have been compared with reflectance spectroscopy measurements.