Pixel non-uniformity correction

Patent metadata

Field	Value
Publication number	US-9936106-B2
Application number	US-201514939449-A
Country	US
Kind code	B2
Filing date	Nov 12, 2015
Priority date	Nov 12, 2015
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

A method of correcting pixel non-uniformity for varying temperature includes determining an FPA temperature and calculating a non-uniformity correction map on a pixel by pixel basis for the FPA, wherein the non-uniformity correction for each pixel is a function of the FPA temperature and empirically derived coefficients. The method also includes applying the non-uniformity correction map at the FPA temperature to condition output of the FPA to produce temperature dependent non-uniformity corrected image data. An imaging system includes a focal plane array (FPA). A temperature sensor is operatively connected to measure FPA temperature. A module is operatively connected to the FPA and temperature sensor to calculate and apply a non-uniformity correction map as described above. There need be no temperature control device for the FPA. The FPA can include a buffered current mirror pixel architecture, and can include an InGaAs material for infrared imaging.

First claim

What is claimed is:

1. A method of correcting pixel non-uniformity for varying temperature comprising:
determining a focal plane array (FPA) temperature;
calculating a non-uniformity correction map on a pixel by pixel basis for the FPA, wherein non-uniformity correction for each pixel is a function of the FPA temperature and empirically derived coefficients; and
applying the non-uniformity correction map to imaging data from the FPA to produce temperature dependent non-uniformity corrected image data, wherein calculating a non-uniformity correction map on a pixel by pixel basis, wherein the non-uniformity correction for each pixel is a function of the FPA temperature and empirically derived coefficients is governed by

δ
⁢

⁢
I
⁢

⁢
c

=

[

p
⁢

⁢
0

+

p
⁢

⁢
1
×
log
⁢

⁢
10
⁢

(
T
)

]

×

(

Iraw
-

∑

n
=
0

,
1
,
3
,
5

⁢

(

a
n

×

(

T
-

T
min

T
max

-

T
min

)

n

)

)

wherein δIc represents the change for a respective pixel from its dark level to a desired correction value, Iraw is the raw value of the pixel in digital numbers, T max and T min are maximum and minimum temperatures, respectively, for normalizing FPA temperature T, and p0, p1, and a 0 , a 1 , a 3 , and a 5 are empirically derived coefficients.

2. The method as recited in claim 1 , wherein applying the non-uniformity correction map is performed without controlling the temperature of the FPA.

3. The method as recited in claim 1 , wherein the function of the FPA temperature and empirically derived coefficients incorporates approximating change in a respective pixel's level to a desired corrected value based on the FPA temperature.

4. The method as recited in claim 1 , wherein the FPA includes a buffered current mirror pixel architecture.

5. The method as recited in claim 1 , wherein the FPA includes an InGaAs material for infrared imaging.

6. An imaging system comprising:
a focal plane array (FPA);
a temperature sensor operatively connected to measure FPA temperature; and
a module operatively connected to the FPA and temperature sensor to apply a non-uniformity correction map on a pixel by pixel basis for the FPA as a function of the FPA temperature and empirically derived coefficients, and to apply the non-uniformity correction map to condition output of the FPA to produce temperature dependent non-uniformity corrected image data, wherein the module is configured to calculate the a non-uniformity correction map on a pixel by pixel basis for the FPA as a function of the FPA temperature and empirically derived coefficients as governed by

δ
⁢

⁢
I
⁢

⁢
c

=

[

p
⁢

⁢
0

+

p
⁢

⁢
1
×
log
⁢

⁢
10
⁢

(
T
)

]

×

(

Iraw
-

∑

n
=
0

,
1
,
3
,
5

⁢

(

Assignees

• Sensors Unlimited Inc

Inventors

• Nazemi Jonathan

Classifications

• H04N25/671 Primary

  for non-uniformity detection or correction · CPC title

• H04N5/3651

  Electricity · mapped topic

• H04N5/2176 Primary

  Electricity · mapped topic

• H04N5/33

  Transforming infrared radiation (cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20) · CPC title

• H04N25/20

  for transforming only infrared radiation into image signals · CPC title