High sensitivity color filter array
View Patent ↗A color filter array (CFA) and image processing system wherein a color filter overlaying an image sensor has a luminance element (i.e. green filter in RGB space, or yellow in CMY space) that is made larger than the other two chrominance elements (i.e. red, blue or cyan, magenta). Additionally, overlaying micro-lenses may be sized to correspond to the relative sizes of the underlying color filters. The optimized filter array is compatible with existing de-mosaic image processing.
1. A color filter array comprising:
at least one first color filter;
at least one second color filter; and
at least one third color filter, wherein the third color filter is a luminance element and has a larger area than the at least one first or second color filter;
wherein each filter is covered by a separate micro-lens, such that a micro-lens covering the at least one third color filter has a larger area than the micro-lenses covering the at least one first color filter or second color filter.
2. The color filter array of claim 1 , wherein the at least one third color filter is approximately twice as larger as the at least one first or second color filter.
3. The color filter array of claim 1 , wherein the color filter array comprises a plurality of third color filters, first color filters and second color filters, and wherein the ratio of third color filters to first and second color filters is 4:2:2, respectively.
4. The color filter array of claim 3 , wherein the total area of the third color filters is greater than the total area of first and second color filters.
5. The color filter array of claim 3 , wherein the first color filter is red, the second color filter is blue and the third color filter is green.
6. The color filter array of claim 3 , wherein the first color filter is cyan, the second color filter is magenta, and the third color filter is yellow.
7. A color filter array overlaying an electronic image sensor, the color filter array comprising:
a plurality of first color filters;
a plurality of second color filters;
a plurality of third color filters, wherein the plurality of third, second and first color filters are arranged in a matrix in a ratio of 4:2:2, respectively, and wherein each third color filter has an area that is larger than an area of a first color or a second color filter;
an array of micro-lenses positioned in alignment with the matrix of filters, wherein each color filter is aligned with a separate micro-lens, and wherein the micro-lenses aligned with the third color filters have an area that is larger than an area of the micro-lenses aligned with the first or second color filters.
8. The color filter array of claim 7 , wherein each third color filter has approximately two times the area of each first color filter.
9. The color filter array of claim 7 , wherein each third color filter has approximately two times the area of each second color filter.
10. The color filter array of claim 7 , wherein the total area of the third color filters is greater than the total area of the first and second color filters.
11. The color filter array of claim 7 , wherein each third color filter is a luminance element and comprises a green filter, each first color filter comprises a red filter, and each second color filter comprises a blue filter.
12. The color filter array of claim 7 , wherein each third color filter is a luminance element and comprises a yellow filter, each first color filter comprises a cyan filter, and each second color filter comprises a magenta filter.
13. The color filter array of claim 7 , wherein the electronic image sensor comprises a plurality of equal sized pixels.
14. An imaging system comprising:
an array of photodiodes arranged in a matrix of pixels, the array of photodiodes forming part of an electronic image sensor, and wherein each pixel is of equal area;
an array of color filters, comprising a first color, a second color and a third color filter arranged in a matrix, the array of color filters arranged in alignment with the array of photodiodes, such that each photodiode is covered by a color filter;
an array of micro-lenses arranged in alignment with the array of color filters and array of photodiodes, such that each photodiode and color filter is covered by a micro-lens;
wherein each third color filter is a luminance element and each third color filter has an area that is larger than an area of each first or second color filter, and the area of a micro-lens covering each third color filter is similarly larger than an area of each micro-lens covering the first and second color filters.
15. The imaging system of claim 14 , wherein a ratio of third color filters to first and second color filers is 4:2:2, respectively.
16. The imaging system of claim 14 , wherein the imaging system is compatible with standard Bayer pattern color filter array de-mosaic processing.
17. The imaging system of claim 14 , wherein each first color filter is red, each second color filter is blue, and each third color filter is green.
18. The imaging system of claim 14 , wherein each first color filter is cyan, each second color filter is magenta, and each third color filter is yellow.