Colour image sensor with white pixels and colour pixels

The colour-image sensor, comprising a matrix of N active photosensitive pixels, a pixel including a photodiode in order to deliver an electrical signal function of the electrical charges generated in the photodiode by light, the matrix being covered with a mosaic of colour filters placed in correspondence with the matrix of pixels in order to form pixels that are what are referred to as coloured pixels coated with a colour filter, the filters being of K different types corresponding to a number K of different colours at least equal to two and the pixels of each colour being distributed in the matrix, the matrix furthermore comprising P pixels, P<N, that are what are referred to as white pixels, not covered with a colour filter and distributed in the matrix, characterized in that the photodiodes of the coloured pixels are constructed differently from the photodiodes of the white pixels, the photodiodes of the coloured pixels having, for infrared wavelengths, a coefficient of conversion of photons into electrical charges significantly lower than the conversion coefficient of the photodiodes of the white pixels for the same wavelengths.