Image restoration and faulty sensor detection and compensation system and process

• US 5,101,271 A
• Filed: 03/30/1990
• Issued: 03/31/1992
• Est. Priority Date: 03/30/1990
• Status: Expired due to Fees

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Andrews, Roland L., Lewins, Lloyd L.
• Primary Examiner(s): Kostak, Victor R.
• Application Number:
  US07/502,345
• Time in Patent Office: 732 Days
• Field of Search: 358/113, 358/139, 358/213.16, 358/213.17, 356/51, 250/332, 250/252.1
• US Class Current: 348/246
• CPC Class Codes: H04N 25/68 applied to defects
• CPC Class Codes: H04N 5/33 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

Abstract

A scene-based image restoration system, method and apparatus calculates a plurality of restoration signals to be combined with a plurality of input signals to produce resultant signals that are substantially equal during a desired time interval. These scene-based image restoration systems and methods can use DC offset signals as scene restoration signals. To enhance results, faulty sensors in the system are detected, and the input signals from them compensated to produce better video images from the signals.

Claims

1. A faulty sensor detection and compensation method, comprising the steps of:

evaluating a plurality of input signals from a plurality of sensors exposed simultaneously to a uniform stimulus with the following steps;

(i) computing an average amplitude of input signals for each sensor from a plurality of input signals generated by each sensor scanning a uniform stimulus,

(ii) computing an average amplitude for a plurality of sensors,

(iii) comparing the average amplitude of each sensor to the average amplitude of said plurality of sensors, and

(iv) identifying sensors whose average amplitude is outside of a desired range, said desired range being related to said average amplitude of said plurality of sensors;

calculating a plurality compensation signals based upon said input signals from said sensor with the following steps;

(i) estimating the values of said compensation signals, said estimated compensation signals being applied to said signal responsive means so as to vary said input signals,

(ii) sampling a plurality of said varied input signals from said plurality of sensors to calculate said plurality of average amplitudes of said varied input signals,

(iii) comparing said average amplitudes for a plurality of sensors with a combined average amplitude of a plurality of sensors within said desired range, and

(iv) repeating said estimating, sampling and comparing steps until a desired set of compensation signals are calculated; and

applying said compensation signals to signal responsive means linked to said input signals so as to vary said input signals, such that a maximum number of said plurality of sensors will provide varied input signals of substantially the same amplitude.

2. A faulty sensor detection and compensation method, comprising the steps of:

evaluating a plurality of input signals from a plurality of sensors exposed simultaneously to a uniform stimulus with the following steps;

(i) computing an average amplitude of input signals for each sensor from a plurality of input signals generated by each sensor scanning a uniform stimulus,

(ii) computing an average amplitude for a plurality of sensors,

(iii) comparing the average amplitude of each sensor to the average amplitude of said plurality of sensors, and

(iv) identifying sensors whose average amplitude is outside of a desired range, said desired range being related to said average amplitude of said plurality of sensors;

calculating a plurality compensation signals based upon said input signals from said sensors with the following steps;

(i) estimating the values of said compensation signals, said estimated compensation signals being applied to said signal responsive means so as to vary said input signals,

(ii) sampling a plurality of said varied input signals from said plurality of sensors to calculate said plurality of average amplitudes of said varied input signals,

(iii) comparing said average amplitudes for a plurality of sensors with a combined average amplitude of a plurality of sensors within said desired range, and

(iv) repeating said estimating, sampling and comparing steps until a desired set of compensation signals are calculated; and

applying said compensation signals to signal selection means, said signal selection means being linked to said input signals, producing a plurality of output signals from a desired selection of said input signals.

3. A faulty sensor detection and compensation method, comprising the steps of:

evaluating a plurality of input signals from a plurality of sensors exposed simultaneously to a uniform stimulus with the following steps;

(i) computing an average amplitude of input signals for each sensor from a plurality of input signals generated by each sensor scanning a uniform stimulus,

(ii) computing an average amplitude for a plurality of sensors,

(iii) comparing the average amplitude of each sensor to the average amplitude of said plurality of sensors, and

(iv) identifying sensors whose average amplitude is outside of a desired range, said desired range being related to said average amplitude of said plurality of sensors;

calculating a plurality compensation signals based upon said input signals from said sensors with the following steps;

(i) estimating the values of said compensation signals, said estimated compensation signals being applied to said signal responsive means so as to vary said input signals,

(ii) sampling a plurality of said varied input signals from said plurality of sensors to calculate said plurality of average amplitudes of said varied input signals,

(iii) comparing said average amplitudes for a plurality of sensors with a combined average amplitude of a plurality of sensors within said desired range, and

(iv) repeating said estimating, sampling and comparing steps until a desired set of compensation signals are calculated; and

applying a first group of said compensation signals to signal responsive means linked to said input signals so as to vary said input signals, such that a maximum number of said plurality of sensors will provide varied input signals of substantially the same amplitude; and

applying a second group of said compensation signals to signal selection means, said signal selection means being linked to said varied input signals, producing a plurality of output signals from a desired selection of said varied input signals.

4. A faulty sensor detection and compensation system, comprising:

means for evaluating a plurality of input signals from a plurality of sensors, each of each sensors simultaneously scanning a uniform stimulus with the following steps;

(i) means for computing an average amplitude of input signals for each sensor from a plurality of input signals generated by each sensor scanning said uniform stimulus,

(ii) means for computing an average amplitude for a plurality of sensors,

(iii) means for comparing the average amplitude of each sensor to the average amplitude of said plurality of sensors, and

(iv) means for identifying sensors whose average amplitude is outside of a desired range, said desired range being related to said average amplitude of said plurality of sensors;

means for calculating a plurality of compensation signals based upon said input signals from said sensors with the following steps;

(i) means for estimating the values of said compensation signals, said estimated compensation signals being applied to said signal responsive means so as to vary said input signals,

(ii) means for sampling a plurality of said varied input signals from said plurality of sensors to calculate said plurality of average amplitudes of said varied input signals,

(iii) means for comparing said average amplitudes for a plurality of sensors with a combined average amplitude of a plurality of sensors within said desired range, and

(iv) means for repeating said estimating, sampling and comparing steps until a desired set of compensation signals has been calculated; and

means for applying said compensation signals to signal responsive means linked to said input signals so as to vary said input signals, such that a maximum number of said plurality of sensors will provide varied input signals of substantially the same amplitude.

5. A faulty sensor detection and compensation system comprising:

means for evaluating a plurality of input signals from a plurality of sensors, each of said sensors simultaneously scanning a uniform stimulus with the following steps;

(i) means for estimating the values of said compensation signals, said estimated compensation signals being applied to said signal responsive means so as to vary said input signals,

(i) means for computing an average amplitude of input signals for each sensor from a plurality of input signals generated by each sensor scanning said uniform stimulus,

(ii) means for computing an average amplitude for a plurality of sensors,

(iii) means for comparing the average amplitude of each sensor to the average amplitude of said plurality of sensors, and

(iv) means for identifying sensors whose average amplitude is outside of a desired range, said desired range being related to said average amplitude of said plurality of sensors;

means for calculating a plurality of compensation signals based upon said input signals from said sensors with the following steps;

(i) means for estimating the values of said compensation signals, said estimated compensation signals being applied to said signal responsive means so as to vary said input signals,

(ii) means for sampling a plurality of said varied input signals from said plurality of sensors to calculate said plurality of average amplitudes of said varied input signals,

(iii) means for comparing said average amplitudes for a plurality of sensors with a combined average amplitude of a plurality of sensors within said desired range, and

(iv) means for repeating said estimating, sampling and comparing steps until a desired set of compensation signals has been calculated; and

means for calculating a plurality of compensation signals based upon said input signals from said sensors with the following steps;

(i) means for estimating the values of said compensation signals, said estimated compensation signals being applied to said signal responsive means so as to vary said input signals,

(ii) means for sampling a plurality of said varied input signals from said plurality of sensors to calculate said plurality of average amplitudes of said varied input signals,

(iii) means for comparing said average amplitudes for a plurality of sensors with a combined average amplitude of a plurality of sensors within said desired range, and

(iv) means for repeating said estimating, sampling and comparing steps until a desired set of compensation signals has been calculated; and

means for applying said compensation signals to signal selection means, said signal selection means being liked to said input signals, producing a plurality of output signals from a desired selection of said input signals.

6. A faulty sensor detection and compensation system, comprising:

means for evaluating a plurality of input signals from a plurality of sensors, each of said sensors simultaneously scanning a uniform stimulus with the following steps;

(i) means for computing an average amplitude of input signals for each sensor from a plurality of input signals generated by each sensor scanning said uniform stimulus,

(ii) means for computing an average amplitude for a plurality of sensors,

(iii) means for comparing the average amplitude of each sensor to the average amplitude of said plurality of sensors, and

(iv) means for identifying sensors whose average amplitude is outside of a desired range, said desired range being related to said average amplitude of said plurality of sensors;

means for calculating a plurality of compensation signals based upon said input signals from said sensor with the following steps;

(i) means for estimating the values of said compensation signals, said estimated compensation signals being applied to said signal responsive means so as to vary said input signals,

(ii) means for sampling a plurality of said varied input signals from said plurality of sensors to calculate said plurality of average amplitudes of said varied input signals,

(iii) means for comparing said average amplitudes for a plurality of sensors with a combined average amplitude of a plurality of sensors within said desired range, and

(iv) means for repeating said estimating, sampling and comparing steps until a desired set of compensation signals has been calculated; and

means for applying a first group of said compensation signals to signal responsive means linked to said input signals so as to vary said input signals, such that a maximum number of said plurality of sensors will provide varied input signals of substantially the same amplitude; and

means for applying a second group of said compensation signals to signal selection means, said signal selection means being linked to said varied input signals, producing a plurality of output signals from a desired selection of said varied input signals.

7. The system of claim 6 comprising:

a FLIR sensor array, said sensor array providing said input signals and containing a plurality of sensors to be evaluated and compensated for;

an analog to digital converter for extracting said data by providing digital representations of amplitudes of said input signals from said sensor array during a scan of a uniform source, said uniform source being contained in the housing of said FLIR sensor array;

an accumulator for calculating the average values of said desired samplings of said amplitudes;

a microprocessor to relate said average values for said samplings to produce a plurality of amplifier gain signals, said amplifier gain signals being said first group of said compensation signals supplying signal responsive means, said signal responsive means being variable gain amplifiers through which said input signals flow; and

at least one memory device for storing said average values and said amplifier gain signals.

8. The system of claim 6 comprising:

a microprocessor coupled to signal selective means, said microprocessor generating said second group of compensation signals, said second group of compensation signals causing said signal selection means linked to said input signals to produce an output based upon said desired selection of said input signals; and

at least one memory device for storing said compensation signals.