This invention relates to the reconstruction of a full colour image from an image mosaic composed of a plurality of image pixels that have one of at least three colour values. The pixels are interleaved in rows and columns across the mosaic with pixels of different colour values to form the mosaic in such a way that each row and column contains pixels of at least two colours. A high spatial frequency luminance image is generated from the mosaic that extends across all pixel locations of the image mosaic. The luminance values of pixels in the high frequency image are adjusted to reduce zippering effects. The adjustment is performed on pixels generated from a particular colour value at least in a first row and/or a first column of the high frequency luminance image according to the luminance values for said pixels and the luminance values of pixels generated from another colour value. A low spatial frequency luminance image is generated from the mosaic for each colour value. After the luminance adjustment the high frequency luminance pixels are combined with each of the low frequency luminance images in order to generate a de-mosaiced image for each of the colour values corresponding to said low frequency luminance images.