1. A process for mapping temperatures in an enclosure during a combustion process, comprising: selecting a spectral band for a multi-spectral image-capturing device; generating an intensity-temperature mapping by performing an intensity-temperature calibration based on an intensity of an image pixel in a field of view (FOV) generated by the multi-spectral image-capturing device, a corresponding temperature measurement, and a selected device setting of the image-capturing device; detecting an emitted radiation based on a first spectral image in the FOV captured by the multi-spectral image-capturing device; determining whether at least one region is poor responsive, which is underexposed or overexposed, such that an accurate temperature is unable to be estimated based on a temperature value associated with the spectral band; and replacing, using a computer processor, temperatures of the at least one poor responsive regions with temperatures from corresponding acceptable regions from at least one other spectral image in order to provide an extended temperature mapping of the enclosure, wherein the extended temperature mapping is of a temperature range wider than that associated with the first spectral image.