Automated system for testing an imaging sensor

• US 5,033,015 A
• Filed: 10/25/1990
• Issued: 07/16/1991
• Est. Priority Date: 08/12/1988
• Status: Expired due to Term

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Zwirn, Robert
• Primary Examiner(s): Dixon, Joseph L.
• Application Number:
  US07/604,386
• Time in Patent Office: 264 Days
• Field of Search: 364/579, 364/550, 364/551.01, 364/525, 364/571.07, 382/18, 382/34, 382/51, 382/53, 382/54, 358/10, 358/139
• US Class Current: 702/116
• CPC Class Codes: G06T 7/0002 Inspection of images, e.g. flaw detection
• CPC Class Codes: H04N 17/002 for television cameras

Abstract

An automated system for testing imaging sensors 10 is disclosed. The automated system 10 provides an accurate and repeatable method for testing imaging sensors. The automated system 10 includes an input circuit 20 for receiving input from an imaging sensor system and providing a signal in response thereto, a processor 30 for operating on said signal and generating data therefrom, and a computer 40 for providing output in response to the data. A specific teaching of the invention includes a method for obtaining data for the lookup table and calculating addresses for the data wherein the addresses are a function of the signal and noise components of the imaging sensor system output, while the data relates to actual responses of human observers.

Claims

1. An automated system for testing a sensor system by evaluating the output of said sensor system with respect to a known target, said automated system comprising:

input means for receiving input from said sensor system and providing a first signal in response thereto;

processing means for operating on said first signal and generating first data therefrom, said processing means including;

filtering means for separating noise from said first signal, said filtering means further including scene averaging means for separating random noise from said first signal to provide a pure signature and first subtracting means for subtracting said first signal from said pure signature to provide a pure noise signal and

means for computing at least one address in response to a function of the pure signature and pure noise components of said first signal; and

table means for providing stored data in response to an input of said address thereto, said stored data being representative of a response of at least one human observer viewing a display of the output of an imaging system in response to a known input.

2. The automated system for testing of claim 1 wherein said input means includes camera means for receiving optical output from said imaging system and providing said first signal in response thereto.

3. The automated system for testing of claim 1 wherein said processing means includes histogram means for determining the portions of said pure noise signal that are within a specified range of values.

4. The automated system for testing of claim 1 wherein said filtering means includes memory means for providing a fixed pattern noise signal from said pure signature.

5. The automated system for testing of claim 4 wherein said filtering means includes second subtracting means for subtracting said fixed pattern noise signal from said pure signature to provide a pure signal.

6. The automated system for testing of claim 5 wherein said processing means includes peak means for detecting the value of said pure signal that is greater than a first value and valley means for detecting the value of said pure signal that is less than a second value.

7. The automated system for testing of claim 1 wherein said table means is a lookup table containing stored data.

8. The automated system for testing of claim 7 wherein a function of said first data is provided as an address to said lookup table and said output is provided from said lookup table in response thereto.

9. The automated system for testing of claim 8 wherein said function of said first data includes a peak value P, a valley value V, and a noise component N.

10. The automated system for testing of claim 9 wherein said function is P-V/P+V.

11. The automated system for testing of claim 9 wherein said function is P+V/N.

12. The automated system for testing of claim 7 wherein said table means includes interpolator means for estimating the values of said stored data from a derived function of said first data.

13. A method for obtaining data representing acceptable imaging sensor system output including the steps of:

(a) separating the input from an imaging sensor system into signal and noise components;

(b) obtaining first values representing acceptable values of said input at a set of spatial frequencies as determined by a chosen group of human observers; and

(c) deriving data as a function of said signal and said noise components at said spatial frequencies corresponding to each value of said first values.

14. An automated system for testing a sensor system by evaluating the output of said sensor system with respect to a known target, said automated system comprising:

input means for receiving input from said sensor system and providing a first signal in response thereto;

processing means for operating on said first signal and generating first data therefrom; and

table means for providing output in response to said first data, said table means including a lookup table, wherein a function of said first data is provided as an address to said lookup table and said output is provided from said lookup table in response thereto, said function of said first data being P-V/P+V where P is a peak value and V is a valley value of said first data.

16. The automated system for testing of claim 14 or 15 wherein said table means includes interpolator means for estimating the values of said stored data from a derived function of said first data.

17. The automated system for testing of claim 14 or 15 wherein said processing means includes filtering means for separating noise from said first signal.

18. The automated system for testing of claim 17 wherein said filtering means includes scene averaging means for separating random noise from said first signal to provide a pure signature.

19. The automated system for testing of claim 18 wherein said filtering means includes first subtracting means for subtracting said first signal from said pure signature to provide a pure noise signal.

20. The automated system for testing of claim 19 wherein said processing means includes histogram means for determining the portions of said pure noise signal that are within specified ranges of values.

21. The automated system for testing of claim 17 wherein said filtering means includes memory means for providing a fixed pattern noise signal from said pure signature.

22. The automated system for testing of claim 21 wherein said filtering means includes second subtracting means for subtracting said fixed pattern noise signal from said pure signature to provide a pure signal.

23. The automated system for testing of claim 22 wherein said processing means includes peak means for detecting the value of said pure signal that is greater than a first value and valley means for detecting the value of said pure signal that is less than a second value.

15. An automated system for testing a sensor system by evaluating the output of said sensor system with respect to a known target, said automated system comprising:

input means for receiving input from said sensor system and providing a first signal in response thereto;

processing means for operating on said first signal and generating first data therefrom; and

table means for providing output in response to said first data, said table means including a lookup table, wherein a function of said first data is provided as an address to said lookup table and said output is provided from said lookup table in response thereto, said function of said first data being P+V/N where P is a peak value, V is a valley value, and N is a noise component of said first data.