Linear Models for Digital Cameras

In this paper we describe methods for testing the linearity and estimating the spectral sensitivities of color sensors in digital cameras. We base our analysis on the response of the Kodak DCS-200 and DCS-420 digital cameras to calibrated spectral input. We use this data to build a linear model of the digital camera and verify it by comparing the actual camera response to calibrated spectral input to output values predicted by the linear model. 1 Introduction The processing of digital color camera data (e.g. color correction, demosaicing, and image restoration) often depends on 1) the assumption that the camera sensor responses are linear with respect to source intensity and 2) apriori knowledge of the camera sensor spectral sensitivity. In this paper we describe methods for testing the camera linearity assumption and estimating the spectral sensitivity of the camera sensors. 2 Camera Linearity The light sensors in many modern digital cameras are based on Charge-Coupled Device (CC..