COMPOUND CAMERA SENSOR AND RELATED METHOD OF PROCESSING DIGITAL IMAGES

• US 20130229540A1
• Filed: 04/22/2013
• Published: 09/05/2013
• Est. Priority Date: 10/21/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Farina, Marco, Mancuso, Massimo, Messina, Giuseppe, Capra, Alessandro, Guarnera, Mirko Ignazio
• Granted Patent: US 9,036,048 B2
• Time in Patent Office: Days
• US Class Current: 348/218.1
• CPC Class Codes: H04N 23/13 with multiple sensors
• CPC Class Codes: H04N 23/60 Control of cameras or camera modules
• CPC Class Codes: H04N 23/698 for achieving an enlarged field of view, e.g. panoramic image capture
• CPC Class Codes: H04N 23/843 Demosaicing, e.g. interpolating colour pixel values
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements

Abstract

In one embodiment, a light sensor includes four cell arrays, one for each color of the Bayer pattern, and four lenses each focusing the light coming from the scene to be captured on a respective cell array. The lenses are oriented such that at least a second green image, commonly provided by the fourth cell array, is both horizontally and vertically shifted (spaced) apart by half a pixel pitch from a first (reference) green image. In a second embodiment, the four lenses are oriented such that the red and blue images are respectively shifted (spaced) apart by half a pixel pitch from the first or reference green image, one horizontally and the other vertically, and the second green image is shifted (spaced) apart by half a pixel pitch from the reference green image both horizontally and vertically.

Claims

1. A light sensor for capturing an image of a scene, comprising:

a multi-cell photo-detector composed of a plurality of cell arrays of cells, each cell defining a pixel of an image and being configured to generate an electric signal representative of an intensity of light impinging thereon;

a plurality of lenses, each configured to capture a similar field of view of the scene and focus the light coming from the scene on the cell arrays, respectively, wherein

each of said lenses is placed at a different physical distance from one of the plurality of cell arrays to define different depths of field, said depths of field being staggered.

2. The light sensor of claim 1, wherein said depths of field are staggered without gaps.

3. The light sensor of claim 1, wherein said depths of field are staggered with gaps.

4. The light sensor of claim 1, wherein said lenses lay in a same plane and said cell arrays are defined on different planes.

5. The light sensor of claim 1, wherein said cell arrays are defined on a same plane and said lenses lay in different planes.

6. The light sensor of claim 1, wherein the plurality of lenses includes four lenses, and the plurality of cell arrays includes a first cell array sensitive to red light, a second cell array sensitive to blue light, and third and fourth cell arrays sensitive to green light, disposed according to a Bayer pattern.

7. The light sensor of claim 6, wherein the lenses focusing light on said third and fourth cells arrays are the closest and the farthest from the respective cell arrays.

8. The light sensor of claim 6, further comprising a processing pipeline coupled to said cell arrays and configured to elaborate image pixels captured by said cell arrays and to output a corresponding Bayer image.

9. A method of generating an RGB image of 2N×

2M pixels of a scene to be captured, comprising;

generating via a light sensor four N×

M monochromatic images of said scene, the monochromatic images including a red image, a blue image, a first green image, and a second green image, the red and blue images being shifted by half a pixel pitch horizontally and vertically, respectively, from said first green image and the second green image being shifted by half a pixel pitch both horizontally and vertically from said first green image;

generating via the light sensor a corresponding 2N×

2M Bayer image having odd rows of pixels that are pixels of the first green image and of the red image, and even rows of pixels that are pixels of the blue image and of the second green image; and

generating via the light sensor an output 2N×

2M RGB image by interpolating said 2N×

2M Bayer image.

10. The method of claim 9, wherein generating via a light sensor four N×

M monochromatic images comprises;

generating the four N×

M monochromatic images via a light sensor including;

a multi-cell photo-detector composed of four cell arrays of cells, each cell defining a pixel of the image and being configured to generate an electric signal representative of the intensity of light impinging thereon, the four cell arrays including a first cell array sensitive to red light, a second cell array sensitive to blue light, and third and fourth cell arrays sensitive to green light; and

first, second, third, and fourth lenses focusing light coming from the scene on the four cell arrays, respectively, the first, second, and fourth lenses having axes that are off parallel from an axis of the third lens, the axes of the first and second lenses being oriented such to generate the red and blue images shifted by half a pixel pitch horizontally and vertically, respectively, from said first green image and the axis of the fourth lens being oriented such to generate the second green image shifted by half a pixel pitch both horizontally and vertically from said first green image

11. A light sensor for capturing an image of a scene, comprising:

a multi-cell photo-detector including first, second, third, and fourth cell arrays of cells, each cell configured to define a pixel of the image and being configured to generate an electric signal representative of an intensity of light impinging thereon; and

four lenses configured to focus light from the scene at first, second, third, and fourth focal points located on the first, second, third, and fourth cell arrays, respectively;

wherein the first, second, and third focal points are positioned at a similar relative locations within the first, the second, and the third cell arrays, respectively; and

wherein the fourth focal point is positioned at a location in the fourth cell array that is shifted one-half pixel horizontally from the relative location of the first focal point in the first cell array, one-half pixel vertically from the relative location of the second focal point in the second cell array, and one-half pixel horizontally and one-half pixel vertically from the relative location of the third focal point in the third cell array.

12. The light sensor of claim 11, wherein the first cell array includes a cell array sensitive to impinging red light, the second cell array includes a cell array sensitive to impinging blue light, and the third and the fourth cell arrays include cell arrays sensitive to impinging green light.

13. The light sensor of claim 12 wherein the cell arrays are disposed according to a Bayer pattern.

14. The light sensor of claim 11 wherein each of the four lenses is configured to capture a similar field of view of the scene and focus the light coming from the scene on one of the cell arrays, respectively, wherein each of the four lenses is placed at a different physical distance from one of the plurality of cell arrays to define different depths of field, said depths of field being staggered.

15. The light sensor of claim 14, wherein said depths of field are staggered without gaps.

16. The light sensor of claim 14, wherein said depths of field are staggered with gaps.

17. The light sensor of claim 14, wherein said lenses lay in a same plane and said cell arrays are defined on different planes.

18. The light sensor of claim 14, wherein said cell arrays are defined on a same plane and said lenses lay in different planes.