Color Transformation and Interpolation for Direct Color Imaging with a Color Filter Array

The DCI (direct color-imaging) approach is promising as an acquisition scheme of color data with high spatial-resolution. The DCI sensor has three photo-sensing layers along its depth direction. Although each pixel has three color channels, their spectral sensitivities are overlapped with each other and the approach has a problem in color separation. To cope with this problem, we present a hybrid color-imaging approach between the DCI approach and the CFA (color-filter-array) approach. Our hybrid approach uses the DCI sensor, and pastes green and magenta color filters on pixels´ surfaces according to a checkered pattern. The use of the green-magenta CFA improves color separation, but its sensed color channels have different spectra from the primary color-matching functions. Moreover, its sensed three color channels are sub-sampled according to the checkered pattern. To recover a primary tri-stimulus image with full spatial-resolution, not only color transformation of the sensed color channels but also their interpolation are needed. We present image recovery methods for the color transformation and the interpolation. Our hybrid color-imaging approach using the methods achieves higher spatial-resolution than the CFA approach, and shows the best color-reproduction among the three color-imaging approaches.