Traitement non linéaire uniforme pour la reconstruction d'une mosaïque chromatique répartie aléatoirement

In the cone mosaic, spatial and chromatic information is mixed, i.e. the achromatic map (defined as the spatial information without chromatic content) is confounded with the chromatic map (distribution of chromatic information at constant luminance). We have previously shown [1] that in case of a regular arrangement of chromatic samples in the mosaic, a linear algorithm is able to extract achromatic spatial information and to interpolate chromatic information. Indeed, the regularity of chromatic samples permits the localization of luminance and chromatic-opponent signals in the Fourier spectrum which in turn permits their separation using uniform linear filtering. However, in the case of an irregular arrangement, luminance and chrominance are no longer localized and a non linear algorithm is needed. Which non linear algorithm is best ? We show that a uniform linear filtering followed by a non linear normalisation of each channel is able to estimate accurately the achromatic information in the cone mosaic.