Processing color and panchromatic pixels

• US 8,274,715 B2
• Filed: 07/28/2005
• Issued: 09/25/2012
• Est. Priority Date: 07/28/2005
• Status: Active Grant

• Current Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Original Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Inventors: Hamilton, John F. Jr., Compton, John T.
• Primary Examiner(s): SARPONG, AKWASI
• Application Number:
  US11/191,538
• Publication Number:
  US 20070024879A1
• Time in Patent Office: 2,616 Days
• Field of Search: 348/276, 348/222, 348/242, 348/229.1, 348/364, 348/272, 348/246, 348/277, 348/362, 348/147, 348/222.1, 348/218.1, 382/110, 382/284, 382/254, 358/518, 358/42, 358/43, 358/44, 358/513, 358/494, 358/474, 358/482
• US Class Current: 358/512
• CPC Class Codes: H04N 23/84 for processing colour signals
• CPC Class Codes: H04N 25/133 including elements passing panchromatic light, e.g. filters passing white light
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements
• CPC Class Codes: H04N 25/135 based on four or more different wavelength filter elements

Abstract

A method for forming a final digital color image includes capturing an image using an image sensor having panchromatic pixels and color pixels corresponding to at least two color photoresponses; providing from the captured image a digital panchromatic image and an intermediate digital color image; and using the digital panchromatic image and the intermediate digital color image to provide the final digital color image.

Claims

1. A method for forming a digital color image comprising:

capturing an image using a solid state image sensor having a pixel array that includes both panchromatic pixels and color pixels, wherein the color pixels correspond to at least two color photoresponses and wherein the pixel array is made up of a plurality of tiled minimal repeating units, each minimal repeating unit including a plurality of cells, each cell including at least two panchromatic pixels and at least two pixels having the same color photoresponse;

grouping signals from all of the color pixels in each cell into one or more group signals to increase color photosensitivity, wherein all pixels whose signals are grouped into a group signal have the same color photoresponse;

combining the group signals to form a low-resolution digital color image having a first resolution based on the resolution of the cells;

using second signals from the individual panchromatic pixels to provide a high-resolution digital panchromatic image having a second resolution based on the resolution of the pixels in the image sensor; and

combining the high-resolution digital panchromatic image and the low-resolution digital color image to provide a high-resolution digital color image.

2. The method of claim 1, wherein each minimal repeating unit includes at least twelve pixels.

3. The method of claim 2, wherein the cells are non-overlapping cells.

4. A method for processing a color image captured by an image sensor to permit the effective reproduction of a color image captured under low lighting conditions, comprising:

(a) using a solid state image sensor to capture an image, the image sensor having a pixel array including both panchromatic pixels and color pixels, wherein the color pixels correspond to at least two color photoresponses, and wherein the pixel array is made up of a plurality of tiled minimal repeating units, each minimal repeating unit including a plurality of cells, each cell including at least two panchromatic pixels and at least two pixels having the same color photoresponse;

(b) grouping signals from all of the color pixels within each cell into one or more group signals to increase color photosensitivity, wherein all pixels whose signals are grouped into a group signal have the same color photoresponse;

(c) combining the group signals to form a low-resolution digital color image having a first resolution based on the resolution of the cells;

(d) using second signals from the individual panchromatic pixels to provide a high-resolution digital panchromatic image having a second resolution based on the resolution of the pixels in the image sensor; and

(e) combining the low-resolution digital color image and the high-resolution digital panchromatic image to produce a high-resolution digital color image.

5. The method of claim 4, wherein element (b) includes summing the first signals from the plurality of pixels having the same color photoresponse in each group.

6. The method of claim 4, wherein element (e) includes:

summing pixel values from the high-resolution panchromatic image to produce a low-resolution panchromatic image having the first resolution;

using the low-resolution panchromatic image and the low-resolution color image to produce a color difference image; and

using the color difference image and the high-resolution panchromatic image to produce a high-resolution color image.

7. The method of claim 5 wherein element (e) includes:

summing pixel values from the high-resolution panchromatic image to produce a low-resolution panchromatic image having the first resolution;

using the low-resolution panchromatic image and the low-resolution partial color image to produce a color difference image; and

using the color difference image and the high-resolution panchromatic image to produce a high-resolution color image.