Dead pixel correction by row/column substitution

• US 6,611,288 B1
• Filed: 02/26/1998
• Issued: 08/26/2003
• Est. Priority Date: 02/26/1998
• Status: Expired due to Term

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Micron Technology, Inc.
• Inventors: Doudoumopoulos, Nick, Fossum, Eric R., Panicacci, Roger
• Primary Examiner(s): MOE, AUNG SOE
• Application Number:
  US09/031,145
• Time in Patent Office: 2,007 Days
• Field of Search: 348/241, 348/246, 348/247, 382/272, 382/254, 382/275, 382/149, 382/205, 382/274, 358/448, 358/447, 358/461
• US Class Current: 348/246
• CPC Class Codes: H04N 25/68 applied to defects

Abstract

Bad pixels areas in an optical device are investigated and corrected. An upper limit on the number of bad areas is defined. Each bad area can be one, or more than one pixel.

Claims

1. An apparatus for detecting an image in pixel format, comprising:

a photosensitive substrate, having an image detection portion operating in pixel units, said substrate including;

a plurality of photodetecting pixels;

a plurality of on chip registers, each register having a pixel address storage area, each said storage area being capable of storing a value indicative of a block of defective pixels, wherein said value comprises a type indicator indicative of a shape of said block of pixels;

a comparing part, comparing current addresses for said pixels with value that are stored in said registers, and producing an output indicative thereof; and

a pixel correction element detecting addresses of bad pixels from said comparing part and which substitutes a different pixel value corresponding to an obtained pixel value based on said output from said comparing part.

2. Apparatus as in claim 1, where said apparatus is an active pixel sensor.

3. Apparatus as in claim 1, wherein said type value is indicative of a non-linear shape including a plurality of adjacent pixels.

4. Apparatus as in claim 3, wherein said non-linear shape comprises an N×

N block of pixels.

10. Apparatus as in claim 1, wherein said indicia comprises a row address, a column address, and a type.

11. Apparatus as in claim 10, wherein the type is selected from one of a row, a column, and a shape of pixels.

5. A pixel correction method, comprising:

initially determining pixels within a pixel array which are not operating according to a predetermined criteria;

defining an indicia of said pixels, wherein said indicia includes an address and a single value which represents a shape of a block of pixels and storing said indicia in a storage element on the same substrate as said pixel array;

determining an address of a current pixel;

comparing, on the same substrate as said pixel array, said address to said indicia in said storage element; and

when a pixel is detected as not operating according to the criteria based on said comparing, replacing the not operating pixel and other pixels in said block of pixels corresponding to the single value with a value of an obtained good pixel.

6. A method as in claim 5, wherein said indicia represents a specified group of pixels, from the group consisting of a single pixel, a row of pixels, or a column of pixels.

7. A method as in claim 5, wherein said taking comprises substituting at least one different pixel for said pixels which are not operating according to the criteria.

8. A method as in claim 5 wherein said obtained pixel is a previously-obtained good pixel.

9. Method as in claim 8 wherein said obtained pixel is the last obtained good pixel.

12. An apparatus for detecting an image in pixel format, comprising:

a photosensitive substrate, having an image detection portion operating in pixel units, said substrate including;

a plurality of photodetecting pixels

a plurality of on chip registers, each register having an address storage area, each said storage area being capable of storing a value indicative of a block of defective pixels, wherein said value comprises a type indicator indicative of a shape of said block of pixels;

a comparing part, comparing current addresses for said pixels with value that are stored in said registers, and producing an output indicative thereof;

an analog to digital converter operative to convert a sampled analog signal from a photodetecting pixel to a digital pixel value;

a digital output; and

a pixel correction element detecting an address of a bad pixel from said comparing part and which replaces a digital pixel value corresponding to a pixel value obtained from said bad pixel with a different digital pixel value corresponding to another obtained pixel value before said pixel value is presented at said digital output, based on said output from said comparing part,

wherein said apparatus is an active pixel sensor including, in each of said pixel units, a photosensor, an in-pixel follower element and in-pixel selection element.

13. Apparatus as in claim 12 wherein said pixel correction element substitutes a last good obtained pixel value for any determined bad value.

14. Apparatus as in claim 12 wherein said address represents a plurality of different pixel values.