"A Novel Color Filter Array and Demosaicking Algorithm for Hexagonal Grids" slides

I have already mentioned my paper in earlier posts. Today I want to share the slides that I used when I presented the paper in China at ICGIP 2014.

"A Novel Color Filter Array and Demosaicking Algorithm for Hexagonal Grids" published

It took quite a while but now our paper "A Novel Color Filter Array and Demosaicking Algorithm for Hexagonal Grids" is online at SPIE. Follow the link to download it.

The main idea presented in this paper is to replace the square grid, which is typically used in digital imaging with a hexagonal grid. This alone is not a new idea, there have been people in the past who thought about using hexagonal pixels. However, we also propose a color filter array for such a grid. Remember, color filter arrays are used to make an image sensor capture color images, by letting every single pixel capture only one of three primary colors. And because this alone is not very helpful, we also provide a demosaicking algorithm for this CFA.

So here´s our CFA:

Hexagonal Color Filter Array

As you can see, its color distribution is very different to that of the Bayer pattern. 6 out of 9 pixels on our grid are green, which allows for very good luminance interpoaltion, without using cross-channel information. There are quite few red and blue pixels on our grid. This does actually not matter in most cases as we can use cross-channel information for the interpolation of these.

Comparison of Color Filter Arrays

Color filter arrays are widely used in digital cameras. Such arrays allow for every pixel on a sensor array to capture only one of the primary colors red, green and blue. The missing color values need to be interpolated. The arrangement of color filters on the sensor array affects the quality of the reconstructed image. The study of alternative color filter arrays is therefor an important task to improve image quality. In this master thesis four color filter arrays are compared. These are the traditional Bayer-pattern, Fuji's X-Trans-pattern, the pattern that Sony uses in it's F65 camera as well as a pattern for hexagonal grids. For each of them specialized demosaicing algorithms have been implemented to achieve the best possible quality. Several sample images have been processed to show the different properties of the color filter arrays. PSNR and SSIM were measured to determine their quality. Based on these measurements and observations no clear recommendation for a CFA can be made. However, advantages and disadvantages of the CFAs are highlighted and discussed.

This is the abstract of my master thesis. I will add more of it in future posts. If you can´t wait to find out more feel free to contact me.