Sparsely sampled image sensing device with color and luminance photosites

• US 6,476,865 B1
• Filed: 03/07/2001
• Issued: 11/05/2002
• Est. Priority Date: 03/07/2001
• Status: Expired due to Term

• Current Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Original Assignee: Eastman Kodak Company
• Inventors: Gindele, Edward B., Gallagher, Andrew C.
• Primary Examiner(s): Garber, Wendy R.
• Assistant Examiner(s): Rosendale, Matthew L
• Application Number:
  US09/800,875
• Time in Patent Office: 608 Days
• Field of Search: 348/270, 348/271, 348/272, 348/273, 348/222, 348/234, 348/277, 348/279, 257/440
• US Class Current: 348/277
• CPC Class Codes: A61B 1/0638 providing two or more wavelengths
• 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

An image sensing device having an array of light-sensitive elements, including: a first type of element sensitive to a spectral region corresponding to luminance; a second type of element sensitive primarily to red light; a third type of element sensitive primarily to green light; and a fourth type of element sensitive primarily to blue light, the four types of elements occurring in repeating patterns.

Claims

1. An image sensing device having an array of light-sensitive elements, comprising a first type of element sensitive to a spectral region corresponding to luminance;

a second type of element sensitive primarily to red light;

a third type of element sensitive primarily to green light; and

a fourth type of element sensitive primarily to blue light, the four types of elements occurring in repeating patterns such that over at least a major portion of the array, all four types of elements occur in equal numbers.

2. The image sensing device claimed in claim 1, wherein the four types of elements occurring in repeating patterns are such that over at least a major portion of the array all four types of elements occur at every other element position along both of two orthogonal directions of the array of light-sensitive elements.

3. A method of capturing a color digital image, comprising the steps of:

a) providing an image sensing device having an array of light-sensitive elements, which array includes at least a first type of element sensitive to a spectral region corresponding to luminance;

a second type of element sensitive primarily to red light;

a third type of element sensitive primarily to green light; and

a fourth type of element sensitive primarily to blue light, the four types of elements occurring in repeating patterns;

b) employing the image sensing device to produce a sparsely sampled digital image; and

c) interpolating missing color pixel values in the sparsely sampled digital image to generate the color digital image having a red, green and blue pixel value for each location in the array by employing a first interpolation technique that uses neighboring luminance values when the neighboring luminance values are not clipped, and a second interpolation technique that does not use neighboring luminance values when the neighboring luminance values are clipped.

4. The method claimed in claim 3, wherein the four types of elements occurring in repeating patterns are such that over at least a major portion of the array all four types of elements occur at every other element position along both of two orthogonal directions of the array of light-sensitive elements.

5. The method claimed in claim 3, wherein the image sensing device is in a camera.

6. The method claimed in claim 5, wherein the interpolation step is performed in the camera.

7. The method claimed in claim 3, wherein the interpolation step includes the steps of:

c1) calculating a first set of interpolated pixel values for each color at each pixel location;

c2) calculating color difference pixel values for each pixel location using the first set of interpolated pixel values; and

c3) calculate a final set of interpolated pixel values using the color difference pixel values.

8. The method claimed in claim 7, wherein the first set of interpolated pixel values are calculated by computing a Laplacian pixel value for pixels of one color and adding the Laplacian pixel value to a pixel value of a different color.

9. The method claimed in claim 7, wherein the final set of interpolated pixel values are calculated for clipped pixels using a nearest neighbor averaging technique.

10. The method claimed in claim 7, wherein the luminance pixel values and the color difference pixel values are used to calculate the final set of interpolated pixel values.