From the Sensor to Color Images

Olivier Losson (1) , Eric Dinet (2)

1 LAGIS-SI
2 LHC - Laboratoire Hubert Curien

This chapter deals with the acquisition of colour images by mono-CCD colour cameras. These devices acquire only one colour component at each pixel through the CFA (Colour Filter Array) that covers the CCD sensor. A procedure - called demosaicing - is necessary to estimate the other two missing colour components at each pixel to obtain a colour image. A mathematical formalization for demosaicing is proposed, before we present some of the methods in the demosaicing literature, as well as the post-processing algorithms to correct the estimated images. We then present objective criteria for the quality evaluation of colour images, and apply them to estimated images to draw up conclusions about the selection of a demosaicing method. At last, we examine why and how white balancing is required and implemented to provide images faithfull to the observed scene under varying illumination conditions.

Mots clés: Color Demosaicing; Bayer CFA; Estimated Image Quality; White Balance Calibration

Domaines: Traitement du signal et de l'image [eess.SP]; Traitement du signal et de l'image [eess.SP]

Olivier Losson, Eric Dinet. From the Sensor to Color Images. Christine Fernandez-Maloigne, Frédérique Robert-Inacio, Ludovic Macaire. Digital Color - Acquisition, Perception, Coding and Rendering, Wiley, pp.149-185, 2012, Digital Image and Signal Processing series. ⟨hal-00705825⟩