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 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, and wherein each third color filter is formed as an octagon.
2. 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 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, and wherein a third color filter has a 2.68 micron pitch and the first and second color filters have a 1.32 micron pitch (square) fitting within the nominal 2 micron pitch of the underlying electronics supporting each pixel.
3. 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; and
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, wherein each third color filter has an area that is larger than an area of a first color or a second color filter, and wherein each third color filter is formed as an octagon.
4. The color filter array of claim 3 , wherein a third color filter has a 2.68 micron pitch and the first color and second color filters have a 1.32 micron pitch (square) fitting within the nominal 2 micron pitch of the underlying electronics supporting each pixel.
5. 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, and wherein a ratio of third color filters to first and second color filers is 4:2:2, respectively, and wherein each third color filter is formed as an octagon.
6. The imaging system of claim 5 , wherein each third color filter has approximately two times the area of a first or second color filter.
7. 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, and wherein each third color filter has approximately twice the area of each first or second color filter, such that the luminance signal-to-noise ratio of the imaging system is increased by 3 dB relative to a standard color filter array pattern.