In most digital cameras, color images are captured by a sensor overlaid by the Bayer color filter array (CFA). Denoisaicking (joint demosaicking and denoising) consists in reconstructing a color image from the noisy "Bayerized" data output by the sensor. We show that the frequency analysis of the sampling pattern induced by the Bayer CFA provides a simple way to reconstruct the luminance and chrominance channels of the image. The process is reduced to adequate linear filtering operations and denoising of the grayscale luminance image.