Spatio-Spectral Modeling and Compensation of Transversal Chromatic Aberrations in Multispectral Imaging

In optical imaging systems, the wavelength-dependency of the refraction indices of lenses causes chromatic aberrations: electromagnetic radiation from an object point is dispersed in a rainbow-like manner on the sensor. These aberrations were so far only measured and modeled for up to three, often relatively wideband wavelength bands like R, G and B. Moreover, no relation between the aberrations of these color channels was generally considered. We describe here the measurement of chromatic aberrations for multiple narrowband color channels in multispectral imaging. We discuss existing models for transversal distortions and analyze the wavelength-dependency of their parameters. We extend the models with univariate wavelength-dependent polynomials, thus leading to bivariate models for both space and wavelength-dependency. We compare the models and confirm their validity qualitatively and quantitatively and simulate aberrations with state-of-the-art raytracing software. With our wavelength-dependent model, the distortions can be compensated even at wavelengths for which no measurements are available.