[Paper] Preserved Color Pixel: high-resolution and high-colorfidelity image acquisition using single image sensor with sub-half-micron pixels

Abstract

A preserved-color-pixel (PCP) concept is proposed. The PCP color filter array (CFA) is arranged to construct "PCP pixels". A PCP pixel is surrounded by “buffer pixels” having color filters of the same color spectrum as that of the PCP pixel, so that most of color cross-talk from pixels of different colors are absorbed by the buffer pixels. The color cross-talk components of the buffer-pixel signals are computationally canceled by a proposed non-parametric method called "similarity-based blind cross-talk correction (SBC)," where signals of PCP pixels are used as the ground truth to estimate the signals of buffer-pixels without influence of the cross-talk. The demosaicing of each color planes' images sampled with a PCP-CFA arrangement is implemented by the adaptive normalized convolution (ANC) in conjunction with the proposed "post-convolutional-variation-minimization (PCVM)" algorithm for its cost function. Both SBC and PCVM-ANC are especially useful for image acquisition with a pixel array in a sub-half-micron generation, where its pixel pitch is approximately, or smaller than, 0.5 μm. The concept is verified with image simulation, and its effectiveness is quantified with the slanted-edge based spatial frequency response (SFR) modular transfer function (MTF) method by using the parametric color cross-talk analysis based on proposed "scalable-single-parameter (SSP)" color cross-talk model. The image simulation confirms the color reproductivity, together with the effectiveness of image resolution improvement under the influence of the complication of color cross-talk between pixels and lateral chromatic aberration (LCA) of the taking-lens. The benefit is also verified by peak-signal-to-noise-ratio (PSNR) analysis with simulated images based on a real-world picture, indicating that the proposed concept can maintain PSNR when color crosstalk increases.