Automatic detection of oblique shocks and simple waves in schlieren images of two-dimensional supersonic steady flows

•Automatic detection of flow structure within schlieren images of supersonic flows.•Accurate Mach number measurements in moderately supersonic flows.•Accurate measurement of position and slope of simple waves and oblique shocks.•Quantitative application of schlieren technique in non-ideal compressible flows.•Experimental characterization of highly non-ideal supersonic flows.