METHOD AND SYSTEM FOR UV INOPERABLE PIXEL COMPENSATION

• US 20160028979A1
• Filed: 07/21/2015
• Published: 01/28/2016
• Est. Priority Date: 07/22/2014
• Status: Active Grant

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Grzeslak, Kazimierz T., Nordhaus, Kurt J., Dolfini, Stephen M.
• Granted Patent: US 9,906,742 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06T 2207/20032 Median filtering
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/77 Retouching; Inpainting; Scratch removal
• CPC Class Codes: H04N 25/683 by defect estimation performed on the scene signal, e.g. real time or on the fly detection
• CPC Class Codes: H04N 5/32 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

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.

Claims

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 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;

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 (A13;

A23;

A33) minus a sum of (A11;

A21;

A31)) divided by a sum of (A13;

A23;

A33;

A11;

A21;

A31); and

where CentroidY equals (a sum of (A11;

A12;

A13) minus a sum of (A31;

A32;

A33)) divided by a sum of (A11;

A12;

A13;

A31;

A32;

A33).

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 compensation algorithm comprises:

guard peak;

median filter;

max kernel slope;

max kernel slope*1.2;

max kernel slope*0.75;

max kernel slope*0.5;

max kernel slope*0.3; and

max corner.

8. The method of claim 7, wherein said guard peak comprises selecting a largest value out of eight pixels in said Kernel inoperable pixel comprising (Maximum of (A11, A12, A13, A21, A23, A31, A32, A33)).

9. The method of claim 7, wherein said Median filter comprises calculating a median value out of eight pixels in said Kernel comprising (Median of (A11, A12, A13, A21, A23, A31, A32, A33)).

10. The method of claim 7, wherein said Max kernel Slope (MSLP) Filter 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 (A11+A33;

A12+A32;

A13+A31;

A21+A23)).

11. The method of claim 7, 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 ((A21+A31+A32) divided by three;

(A21+A11+A12) divided by three;

(A12+A13+A23) divided by three;

(A23+A33+A32) divided by three).

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

13. 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.

14. The method of claim 1, wherein said step of applying a compensation algorithm 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.

15. 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;

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.

16. The system of claim 15, wherein said kernel comprises a three by three block of eight pixels surrounding said inoperable pixel.

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

18. The system of claim 15, 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.

19. The system of claim 15, wherein said compensation algorithm filter selection is based on one of eight centroid value ranges.

20. 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 ii 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 said inoperable pixel with output of said UV sensor array, whereby noise is reduced by a factor of four and random sources are prevented from appearing in output of said array.