Recently, a CFA sensor including a W channel has been developed. Since the W channel receives brightness information, it has a broad spectrum band compared to primary colors (Red, Green, Blue) and exhibits a high SNR. A camera using the CFA sensor obtains only certain type of color information for each pixel, so a color interpolation method is used to restore the full resolution image. In this paper, we propose a new color interpolation method for Sony-RGBW CFA. The proposed method is edge-adaptive and preferentially restores the W channel with a high sampling rate. In the next step, the R, G, and B channels are restored in the color difference domain using the W channel with the full resolution. Experimental results showed that the reconstructed image obtained by applying the proposed algorithm to the Sony-RGBW is superior to the image restored by conventional method in terms of SNR and visual confirmation.
Inverse quadratic problem of joint demosaicing and multiframe super-resolution(SR) was considered. Closed form solutions for different constant sub-pixel motions between frames were obtained and represented in the form of filter bank, which allows to compute solution of SR problem using adaptive filtering, where filters are selected depending on sub-pixel motion between frames. This procedure can be carried out using single iteration. For directional and non-directional parts of image corresponding directional or non-directional filters were applied. Color artifact reduction was achieved via usage of linear cross-channel regularizing term inspired by popular demosaicing methods. The framework includes motion estimation in Bayer domain, integrated noise reduction sub-algorithm, directionality estimation sub-algorithm, fallback logics and post-processing for additional color artifact reduction. Bank of filters is computed offline using specially developed compression techniques, which allows to reduce number of actually stored filters. Developed solution had shown superior results, compared to subsequent demosaicing and single channel SR and was tested on real raw images captured by cell phone camera in burst mode.