With the objective of achieving better investigation of engines-fuels by obtaining instantaneous quantitative imaging of in-cylinder processes, several steps have been taken for some years at Rutgers University. They are: (1) Construction of a new multispectral high-speed infrared (IR) digital imaging system; (2) Development of spectrometric analysis methods; (3) Application of the above to real-world in-cylinder engine environments and simple flames. This paper reports some of results from these studies.The one-of-a-kind Rutgers IR imaging system was developed in order to simultaneously capture four geometrically (pixel-to-pixel) identical images in respective spectral bands of IR radiation issued from a combustion chamber at successive instants of time and high frame rates.In order to process the raw data gathered by this Rutgers system, three new spectrometric methods have been developed to date: (1) dual-band mapping method; (2) new band-ratio method; and (3) three-band iteration method. The former two methods were developed to obtain instantaneous distributions of temperature and water vapor concentrations, and the latter method is to simultaneously find those of temperature, water vapor and soot in gaseous mixtures, i.e., to achieve quantitative imaging.Applications of these techniques were made to both SI and CI engine combustion processes as well as bench-top burner flames. Discussion is made on the methods and new results.