Real-time opto-electronic image processor

• US 6,353,673 B1
• Filed: 04/27/2000
• Issued: 03/05/2002
• Est. Priority Date: 04/27/2000
• Status: Expired due to Term

• Current Assignee: Intellisense Systems, Inc.
• Original Assignee: Physical Optics Corporation
• Inventors: Sandomirsky, Sergey, Shnitser, Paul I., Avakian, Aramais, Agurok, Ilʼya
• Primary Examiner(s): ROGERS, SCOTT A
• Application Number:
  US09/560,412
• Time in Patent Office: 677 Days
• Field of Search: 382/103, 382/191, 382/260, 382/261, 382/275, 382/274, 348/169, 359/308, 356/326
• US Class Current: 382/103
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06V 10/255 Detecting or recognising potential candidate objects based on visual cues, e.g. shapes
• CPC Class Codes: G06V 10/30 Noise filtering
• CPC Class Codes: G06V 10/88 Image or video recognition using optical means, e.g. reference filters, holographic masks, frequency domain filters or spatial domain filters

Abstract

A system and method for real time optical processing of images by simultaneous combining the variable set of images in selected spectral intervals. Spectral images at a plurality of spectral intervals are collected if needed. According to criteria established in a particular application, coefficients for an optimal combination of selected spectral intervals are calculated. Positive and negative images are continuously captured through the optical filter whose transmission spectrum adjusted to positive and negative coefficients of the optimal combination. Negative images are subtracted from positive images and a sequence of resulting optimized images is displayed in real time.

Claims

1. A method of real-time optical processing of images by simultaneously combining a variable set of images in various orientations of light polarization and in selected spectral intervals comprising the steps of:

turning a liquid crystal achromatic rotator of light polarization off;

selecting a set of spectral intervals;

adjusting transmitting spectrum of an optical filter to a first selected spectral interval;

acquiring a spectral image through the adjusted optical filter;

turning the liquid crystal achromatic rotator of light polarization on;

repeating the above steps for orthogonal light polarizations, for each selected spectral interval;

defining an object area;

extracting object and background spectral-polarimetric parameters from the set of spectral-polarimetric images;

calculating an optimal set of weight coefficients for each spectral-polarimetric interval satisfying application criteria;

adjusting a filter transmission spectrum to positive weight coefficients for corresponding spectral intervals to create a positive filter;

capturing an image through the positive filter at a relevant polarization;

adjusting a filter transmission spectrum to negative weight coefficients for corresponding spectral intervals to create a negative filter;

capturing an image through the negative filter at a relevant polarization;

subtracting the image captured through the negative filter from the image captured through the positive filter;

recording and displaying the resulting image.

2. The method of claim 1, further comprising cycling through the method of real time optical processing of images, wherein an orientation of light linear polarization and at least one of the number of spectral intervals, their position and the spectral width of each of these intervals can be varied in each cycle.

3. The method of claim 1, further comprising:

monitoring spectral parameters of background of an image;

determining if the background spectral parameters deviate significantly from established background spectral parameters; and

reextracting the object and background spectral parameters if the background spectral parameters deviate significantly from the established background spectral parameters.

4. A system for real-time optical processing of images by simultaneously combining a set of images in different orientations of light linear polarization, in selected spectral intervals comprising:

an objective lens;

a liquid crystal achromatic rotator of light polarization;

an acousto-optic tunable filter coupled to the objective lens;

an image capture device coupled to the acousto-optic tunable filter;

a liquid crystal achromatic rotator of light polarization driver;

a multi-frequency generator connected to the acousto-optic tunable filter; and

a processor coupled to the multi-frequency generator which controls the multi-frequency generator and the liquid crystal achromatic rotator of light polarization driver, calculates object and background spectral parameters, monitors changes of background spectral parameters, calculates weight coefficients for optimal image processing, and performs image subtraction.

5. A method for real time optical enhancement of imaging contrast between an object and a background comprising the steps of:

establishing object and background spectral-polarimetric parameters;

calculating filter coefficients based upon the object and background spectral-polarimetric parameters for maximizing contrast between the object and background in real time;

adjusting an acousto-optic filter transmission spectrum based upon the calculated filter coefficients; and

capturing an image through a relevant orientation of the liquid crystal achromatic rotator of light polarization and an acousto-optic filter having the transmission spectrum based upon the calculated filter coefficients.

6. The method of claim 5, further comprising choosing initial orientations of light polarization and wavelengths for analysis.

7. The method of claim 5, further comprising:

monitoring the background spectral-polarimetric parameters of an image;

determining if the background spectral-polarimetric parameters deviate significantly from the established background spectral-polarimetric parameters; and

reestablishing the object and background spectral-polarimetric parameters if the background spectral-polarimetric parameters deviate significantly from the established background spectral-polarimetric parameters.

8. The method of claim 7, wherein the step of determining if the background spectral-polarimetric parameters deviate significantly from the established background spectral-polarimetric parameters compares the background spectral-polarimetric parameters to a background vector.

9. The method of claim 5, further comprising targeting an object area on a spectral image, wherein the step of establishing the object and background spectral-polarimetric parameters establishes the object and background spectral-polarimetric parameters based on the targeted spectral area.

10. The method of claim 5, wherein the step of capturing an image through the optical filter corresponding to a set of the calculated filter coefficients subtracts images captured through one filter from images captured through another filter.

11. The method of claim 5, further comprising displaying the image captured through the optical filter corresponding to a set of the calculated filter coefficients.

12. A method for real time optical enhancement of imaging contrast comprising the steps of:

acquiring a set of real time images;

creating a translation from the set of real time images into a spectral-polarimetric representation of the set of real time images by using a liquid crystal achromatic rotator or light polarization and an acousto-optic filter;

processing the spectral-polarimetric representation of the set of real time images into positive and negative discrete spectral coefficients to create a high contrast image determinant adaptive spectral-polarimetric filter; and

translating the spectral-polarimetric representation of the set of real time images into a high contrast image using the high contrast image determinant adaptive spectral-polarimetric-filter.

13. The method of claim 12, further comprising choosing initial orientations of light polarization and wavelengths for use in creating the translation.

14. The method of claim 12, further comprising:

monitoring background spectral-polarimetric parameters of an image;

determining if the background spectral-polarimetric parameters deviate significantly from established background spectral-polarimetric parameters; and

recreating a translation, reprocessing the spectral-polarimetric representation and retranslating the spectral-polarimetric representation if the background spectral-polarimetric parameters deviate significantly from the established background spectral-polarimetric-parameters.

15. The method of claim 14, wherein the step of determining if the background spectral-polarimetric parameters deviate significantly from the established background spectral-polarimetric parameters compares the background spectral-polarimetric parameters to a background vector.

16. The method of claim 12, further comprising targeting an object area on a spectral image.

17. The method of claim 12, further comprising subtracting images captured through a positive discrete spectral-polarimetric coefficient filter coefficient from images captured through a negative discrete spectral-polarimetric coefficient filter.

18. The method of claim 12, further comprising storing and displaying the high contrast image.

19. A system for optical enhancement of imaging contrast comprising:

an objective lens;

a liquid crystal achromatic rotator of light polarization;

an acousto-optic tunable filter coupled to the objective lens;

an image capture device coupled to the acousto-optic tunable filter;

a liquid crystal achromatic rotator of light polarization driver;

a multi-frequency generator connected to the acousto-optic tunable filter; and

a processor coupled to the multi-frequency generator which controls liquid crystal achromatic rotator of light polarization the operation, and calculates filter coefficients for the multi frequency generator.

20. The system according to claim 19, wherein the multi-frequency generator comprises an acousto-optic tunable filter driver.

21. The system according to claim 19, wherein the image capture device comprises a photodetector array that receives a filtered image from the acousto-optic tunable filter.

22. The system according to claim 21, wherein the processor receives multiple filtered images from the image capture device and the processor further combines the multiple filtered images to create a high contrast image.

23. The system according to claim 22, further comprising a monitor coupled to the processor that displays the high contrast image created by the processor.

24. The system according to claim 19, further comprising a frame grabber coupled to the image capture device.

25. The system according to claim 19, wherein the acousto-optic tunable filter receives an image from the objective lens, the liquid crystal achromatic rotator of light polarization and the multi-frequency generator drives the acousto-optic tunable filter to filter the image according to the filter coefficients calculated by the processor.

26. A method of real-time optical processing of images by simultaneously combining a variable set of images in selected spectral intervals comprising the steps of:

selecting a set of spectral intervals;

adjusting transmitting spectrum of an optical filter to a first selected spectral interval;

acquiring a spectral image through the adjusted optical filter;

repeating the above steps for each selected spectral interval;

defining an object area;

extracting object and background spectral parameters from the set of spectral images;

monitoring spectral parameters of the background of an image;

determining if the background spectral parameters deviate significantly from established background spectral parameters; and

reextracting the object and background spectral parameters if the background spectral parameters deviate significantly from the established background spectral parameters;

calculating an optimal set of weight coefficients for each spectral interval satisfying application criteria;

adjusting a filter transmission spectrum to positive weight coefficients for corresponding spectral intervals to create a positive filter;

capturing an image through the positive filter;

adjusting a filter transmission spectrum to negative weight coefficients for corresponding spectral intervals to create a negative filter;

capturing an image through the negative filter

subtracting the image captured through the negative filter from the image captured through the positive filter;

recording and displaying the resulting image.

27. The method of claim 26, further comprising cycling through the method of real time optical processing of images, wherein at least one of the number of spectral intervals, their position and the spectral width of each of these intervals can be varied in each cycle.

28. The methods of claim 26, further comprising acquiring a set of spectral images in various light polarizations.

29. A method for real time optical enhancement of imaging contrast comprising the steps of:

acquiring a set of real time images;

creating a translation from the set of real time images into a spectral representation of the set of real time images by using an acousto-optic filter;

processing the spectral representation of the set of real time images into positive and negative discrete spectral coefficients to create a high contrast image determinant adaptive spectral filter;

monitoring background spectral parameters of an image;

determining if the background spectral parameters deviate significantly from established background spectral parameters;

recreating a translation, reprocessing the spectral representation and retranslating the spectral representation if the background spectral parameters deviate significantly from the established background spectral parameters; and

translating the spectral representation of the set of real time images into a high contrast image using the high contrast image determinant adaptive spectral filter.

30. The method of claim 29, further comprising choosing initial wavelengths for use in creating the translation.

31. The method of claim 29, wherein the step of determining if the background spectral parameters deviate significantly from the established background spectral parameters compares the background spectral parameters to a background vector.

32. The method of claim 29, further comprising targeting an object area on a spectral image.

33. The method of claim 29, further comprising subtracting images captured through a positive discrete spectral coefficient filter coefficient from images captured through a negative discrete spectral coefficient filter.

34. The method of claim 29, further comprising storing and displaying the high contrast image.