This work presents the results of an intensity-based fuel air calibration for a range of charge pressures for gasoline fuel. The radical intensity ratio of diatomic carbon (C-2(*)) to methylidene (CH*) was acquired through line-of-sight chemiluminescence imaging at pressures up to 10 bar. Certified gasoline (99% iso-octane, 0.9% n-heptane, and 0.1% other additives) and air are injected into an optically accessible pressure vessel capable of handling pressures up to 200 bar and ignited with an automotive spark plug. Line-of-sight images of C-2(*) and CH* are recorded simultaneously on a single image sensor utilizing an intensifier, a high-speed camera, and various optical components to split the light signals associated with C-2(*) and CH* (centered at 513 and 427 nm, respectively). The ratio of the signals (C-2(*)/CH*) are acquired and compared to the measured equivalence ratio of the exhaust gases and charge pressure. The approach allowed for characterization of the behavior of the intensity ratio at various charge pressures for gasoline. The comparison of the intensity ratio (C-2(*)/CH*), equivalence ratio, and charge pressure resulted in the generation of a correlation map that can be used to calculate equivalence ratio if intensity ratio and charge pressure are known.