Method and system for UV inoperable pixel compensation

Patent metadata

Field	Value
Publication number	US-9906742-B2
Application number	US-201514804746-A
Country	US
Kind code	B2
Filing date	Jul 21, 2015
Priority date	Jul 22, 2014
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

A method for estimating values lost to inoperable pixels on ultraviolet (UV) sensor arrays comprising identifying an inoperable pixel on a UV sensor array, applying a three by three kernel to the inoperable pixel, the three by three kernel being centered on the inoperable pixel, acquiring a centroid value for the inoperable pixel, applying a compensation algorithm based on the three by three kernel radial centroid value, and calculating estimated values for the inoperable pixel.

First claim

What is claimed is:

1. A method for estimating values lost to inoperable pixels on an ultraviolet (UV) sensor array, the method comprising:
identifying one said inoperable pixel on said ultraviolet (UV) sensor array having pixels;
applying a kernel to said inoperable pixel;
acquiring a centroid value for said inoperable pixel;
applying a compensation algorithm to said kernel, wherein said compensation algorithm further comprises:
applying a Guard Peak function multiplied by 1.1 to said kernel if the centroid value is between 0-0.1755;
applying a Max(Corner) function to said kernel if the centroid value is between 0.1755-0.2351;
applying a Max Kernel Slope (MSLP) function multiplied by 1.2 to said kernel if the centroid value is between 0.2351-0.4534;
applying said MSLP function to said kernel if the centroid value is between 0.4534-0.6164;
applying said MSLP multiplied by 0.75 to said kernel if the centroid value is between 0.6164-0.7637;
applying said MSLP multiplied by 0.5 to said kernel if the centroid value is between 0.7637-0.8829;
applying MSLP multiplied by 0.3 to said kernel if the centroid value is between 0.8829-0.9740; and
applying a Median Filter to said kernel if the centroid value is greater than 0.9740, calculating estimated values for said inoperable pixel; and

outputting said estimated value for said inoperable pixel with output of said UV sensor array.

2. The method of claim 1 , wherein said compensation algorithm filter is based on said centroid value wherein said Centroid value equals a square root of ((CentroidX multiplied by CentroidX) plus (CentroidY multiplied by CentroidY));
where CentroidX equals (a sum of (A 13 ; A 23 ; A 33 ) minus a sum of (A 11 ; A 21 ; A 31 )) divided by a sum of (A 13 ; A 23 ; A 33 ; A 11 ; A 21 ; A 31 ); and
where CentroidY equals (a sum of (A 11 ; A 12 ; A 13 ) minus a sum of (A 31 ; A 32 ; A 33 )) divided by a sum of (A 11 ; A 12 ; A 13 ; A 31 ; A 32 ; A 33 ).

3. The method of claim 1 , wherein dimensions of said kernel are three by three.

4. The method of claim 1 , wherein said kernel is centered on said inoperable pixel.

5. The method of claim 2 , comprising eight centroid value ranges.

6. The method of claim 5 wherein said eight centroid value ranges are about 0 to about 0.1755; about 0.1755 to about 0.2351; about 0.2351 to about 0.4534; about 0.4534 to about 0.6164; about 0.6164 to about 0.7637; about 0.7637 to about 0.8829; about 0.8829 to about 0.9740; and greater than about 0.9740.

7. The method of claim 1 , wherein said Guard Peak function comprises selecting a largest value out of eight pixels in said Kernel inoperable pixel comprising (Maximum of (A 11 , A 12 , A 13 , A 21 , A 23 , A 31 , A 32 , A 33 )).

8. The method of claim 1 , wherein said Median filter comprises calculating a median value out of eight pixels in said kernel comprising (Median of (A 11 , A 12 , A 13 , A 21 , A 23 , A 31 , A 32 , A 33 )).

9. The method of claim 1 , wherein said Max Kernel Slope (MSLP) function selects a largest of an opposite kernel's pixel sums and applies half of a selected value as a result, wherein (MSLP equals one half times a Maximum of (A 11 +A 33 ; A 12 +A 32 ; A 13 +A 31 ; A 21 +A 23 )).

10. The method of claim 1 , wherein said Max Corner (MaxCrn) equals a maximum of an average of each corner pixel and each corner pixel's two adjacent pixels of said kernel, where MaxCrn equals Maximum of ((A 21 +A 31 +A 32 ) divided by three; (A 21 +A 11 +A 12 ) divided by three; (A 12 +A 13 +A 23 ) divided by three; (A 23 +A 33 +A 32 ) divided by three).

11. The method of claim 3 , wherein said kernel comprises eight pixels surrounding an inoperable pixel.

12. The method of claim 1 , wherein a value of said inoperable pixel is replaced with a value of zero if said kernel is positioned over pure noise, regardless of said centroid value.

13. A system for estimating values lost to inoperable pixels on an ultraviolet (UV) sensor array comprising:
identifying at least one said inoperable pixel on said UV sensor array;
applying a kernel to one of said at least one inoperable pixels;
acquiring a centroid value for said one inoperable pixel;
applying a compensation algorithm to said kernel, wherein said step of applying a compensation algorithm further comprises:
applying a Guard Peak function multiplied by 1.1 to said kernel if the centroid value is between 0-0.1755;
applying a Max(Corner) function to said kernel if the centroid value is between 0.1755-0.2351;
applying a Max Kernel Slope (MSLP) function multiplied by 1.2 to said kernel if the centroid value is between 0.2351-0.4534;
applying said MSLP function to said kernel if the centroid value is between 0.4534-0.6164;
applying said MSLP multiplied by 0.75 to said kernel if the centroid value is between 0.6164-0.7637;
applying said MSLP multiplied by 0.5 to said kernel if the centroid value is between 0.7637-0.8829;
applying MSLP multiplied by 0.3 to said kernel if the centroid value is between 0.8829-0.9740; and
applying a Median Filter to said kernel if the centroid value is greater than 0.9740;

calculating an estimated value for said one inoperable pixel;
repeating said steps for subsequent inoperable pixels; and
outputting said estimated value for said inoperable pixels with output of said UV sensor array, whereby added noise is reduced by a factor of four and random sources are prevented from appearing in output of said array.

14. The system of claim 13 , wherein said kernel comprises a three by three block of eight pixels surrounding said inoperable pixel.

15. The system of claim 13 , wherein said kernel is centered on said inoperable pixel.

16. The system of claim 13 , wherein a value of said inoperable pixel is replaced with a value of zero if said kernel is positioned over pure noise, regardless of said centroid value.

17. The system of claim 13 , wherein said compensation algorithm filter selection is based on one of eight centroid value ranges.

18. An ultraviolet (UV) sensor array system for estimating values lost to inoperable pixels comprising:
identifying one said inoperable pixel on said UV sensor array having pixels;
applying a 3×3 kernel to said inoperable pixel, said 3×3 kernel being centered on said inoperable pixel;
acquiring a centroid value for said inoperable pixel;
applying a compensation algorithm to said kernel, said compensation algorithm comprising:
applying a Guard Peak function multiplied by 1.1 to said kernel if the centroid value is between 0-0.1755;
applying a Max(Corner) function to said kernel if the centroid value is between 0.1755-0.2351, wherein MaxCrn function equals a maximum of an average of each corner pixel and each corner pixels two adjacent pixels of said kernel;
applying a Max Kernel Slope (MSLP) function multiplied by 1.2 to said kernel if the centroid value is between 0.2351-0.4534, wherein said MSLP function equals half of a maximum value of a sum of pixels and their opposites along said kernel;
applying said MSLP function to said kernel if the centroid value is between 0.4534-0.6164;
applying said MSLP multiplied by 0.75 to said kernel if the centroid value is between 0.6164-0.7637;
applying said MSLP multiplied by 0.5 to said kernel if the centroid value is between 0.7637-0.8829;
applying MSLP multiplied by 0.3 to said kernel if the centroid value is between 0.8829-0.9740; and
applying a Median Filter to said kernel if the centroid value is greater than 0.9740;

calculating estimated values for said inoperable pixel; and
outputting said estimated value for sai

Assignees

• Bae Systems Information & Electronic Systems Integration Inc
• Bae Sys Inf & Elect Sys Integ

Inventors

• Grzeslak Kazimierz T
• Dolfini Stephen M
• Nordhaus Kurt J

Classifications

• G06T5/20

  using local operators · CPC title

• H04N25/683 Primary

  by defect estimation performed on the scene signal, e.g. real time or on the fly detection · CPC title

• G06T2207/20032

  Median filtering · CPC title

• G06T5/005

  Physics · mapped topic

• H04N5/32

  Transforming X-rays (cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30) · CPC title