Color image demosaicking: An overview Daniele Menon Ã , Giancarlo Calvagno Department of Information Engineering, University of Padova, via Gradenigo 6B, 35131 Padova, Italy article info Article history: Received 9 July 2009 Accepted 6 April 2011 Available online 4 May 2011 Keywords: Demosaicking Bayer pattern Color ﬁlter array interpolation Digital cameras abstract Demosaicking is the process of reconstructing a full-resolution color image from the sampled data acquired by a digital camera that apply a color ﬁlter array to a single sensor. This paper discusses the need of a color ﬁlter array and presents a survey of several techniques proposed to demosaicking. A comparison between the different methods is also provided, discussing their performances. & 2011 Elsevier B.V. All rights reserved. 1. Introduction In a typical digital camera each pixel is equipped with a sensor and a microlens that locally focuses the light away from circuitries and toward the photosensitive element of the sensor, usually a CMOS (complementary metal oxide silicon) or a CCD (charge-coupled device). Each CMOS active pixel sensor contains a photodetector and an active ampli- ﬁer to measure the intensity of the light, while the CCD sensors rely on the electron-hole pair that is generated when a photon strikes silicon [1]. In a color digital camera the acquisition may require three sensors per pixel, each of them was sensitive to a particular wavelength. However, the positioning of the sensors is not straightforward. The sensors can be placed over a plane and the light entering the camera split in each pixel and projected onto each spectral sensor, but this solution is expensive and leads to some phase delay between the components. Another approach is to stack the color sensors on top of one another, as done in the Foveon cameras [2], but this arrangement increases the exposure time because the light has to penetrate three levels of silicon. Therefore, most of the digital cameras use a single sensor technique, with a grid of different color sensors, called color ﬁlter array (CFA). The most common pattern for the CFA has been introduced by Bayer [3], and it samples the green band using a quincunx grid, while red and blue are obtained by a rectangular grid, as shown in Fig. 1(a). In this way, the density of the green samples is twice than that of the red and blue channels. This arrangement has been used by most of the digital cameras, for instance in the Canon EOS 500D, Olympus E-450, Lumix DMC-FS12, FS62 and FS42, Sony Alpha 230, 330 and 380 and many others. The Bayer pattern can be applied also using the subtractive primaries cyan, magenta, and yellow (CMY), as in the Kodak DSC620  that have the advantage of being more sensitive to light. Another CFA conﬁguration has been used by Sony in the DSC F828 digital camera, exploiting also the Emerald ﬁlter, while many companies use a cyan, magenta, yellow, and green array (CMYG), to provide a compromise between maximum light sensitiv- ity and high color quality (such as in the Nikon Coolpix 990). Moreover, a yellow, cyan, green, unﬁltered array originated at Hitachi is used by JVC in some of its video cameras. Several other arrangements have been proposed in the literature, such as the pattern shown in Fig. 1(b), presented in [4] or the new scheme introduced by Kodak [5], involving panchromatic pixels as in Fig. 1(c). Recently, Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/image Signal Processing: Image Communication 0923-5965/$ - see front matter & 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.image.2011.04.003 Ã Corresponding author. Tel.: þ39 049 827 7641; fax: þ39 049 827 7699. E-mail addresses: menond@dei.unipd.it (D. Menon), calvagno@dei.unipd.it (G. Calvagno). Signal Processing: Image Communication 26 (2011) 518–533