  Image denoising and demosaicking are the most important early stages in
digital camera pipelines. They constitute a severely ill-posed problem that
aims at reconstructing a full color image from a noisy color filter array (CFA)
image. In most of the literature, denoising and demosaicking are treated as two
independent problems, without considering their interaction, or asking which
should be applied first. Several recent works have started addressing them
jointly in works that involve heavy weight CNNs, thus incompatible with low
power portable imaging devices. Hence, the question of how to combine denoising
and demosaicking to reconstruct full color images remains very relevant: Is
denoising to be applied first, or should that be demosaicking first? In this
paper, we review the main variants of these strategies and carry-out an
extensive evaluation to find the best way to reconstruct full color images from
a noisy mosaic. We conclude that demosaicking should applied first, followed by
denoising. Yet we prove that this requires an adaptation of classic denoising
algorithms to demosaicked noise, which we justify and specify.
