Wide-band image enhancement

• US 6,611,618 B1
• Filed: 01/22/1999
• Issued: 08/26/2003
• Est. Priority Date: 11/13/1997
• Status: Expired due to Term

• Current Assignee: The Schepens Eye Research Institute Inc (Mass General Brigham, Inc.)
• Original Assignee: The Schepens Eye Research Institute Inc (Mass General Brigham, Inc.)
• Inventors: Peli, Eliezer
• Primary Examiner(s): ROGERS, SCOTT A
• Application Number:
  US09/234,846
• Time in Patent Office: 1,677 Days
• Field of Search: 382/254, 382/154, 382/190, 382/195, 382/199, 382/260, 382/266, 382/274, 382/291, 382/294, 348/62, 345/632, 345/633
• US Class Current: 382/154
• CPC Class Codes: G06T 2207/20056 Discrete and fast Fourier transform, [DFT, FFT]
• CPC Class Codes: G06T 5/10 using non-spatial domain filtering
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening

Abstract

An image processing technique produces modified images by extracting strong features of the original image, i.e., bars and edges, and superimposing such extracted features onto the original image. The invention combines the Hilbert transform of the image data with the image data in a pre-defined manner to produce the so-called energy function whose maxima correspond to the strong features of the image. Addition of these extracted features to the original image results in obtaining an enhanced image. In addition, the invention provides techniques for enhancing the real-world view of natural scenes. Another practice of the invention employs a plurality of oriented filters for extracting luminance features of an image. An apparatus of the invention displays the extracted luminance features as contour version of the original image. Another apparatus of the invention provides a minified contour image of a natural scene to assist a patient having a restricted peripheral vision in locating objects in the scene.

Claims

1. A method for real-time modification of a natural scene for a human observer, said method comprising the steps of:

obtaining an image of said natural scene;

extracting features of said image selected from the group consisting of local maximum luminance, local minimum luminance and transitions between regions of varying luminance;

manipulating said extracted features to obtain modified features; and

projecting said modified features onto a semi-transparent screen disposed in front of an eye of said observer to enable simultaneous viewing of both the natural scene and the modified features by said observer.

2. The method of claim 1, wherein said image of said natural scene is a video image.

3. The method of claim 1, wherein said image of said natural scene is an image within the visual spectrum.

4. The method of claim 1, wherein, in said projecting step, said semi-transparent screen is part of a television or movie screen.

5. The method of claim 1, wherein, in said projecting step, said semi-transparent screen is part of a see-through head mounted display.

6. The method of claim 1, wherein, in said projecting step, said semi-transparent screen is a plane between the observer and the scene.

7. The method of claim 6, wherein said plane is an automobile or an airplane windshield.

8. The method of claim 1, wherein said projected modified features are the same size as and aligned with said image.

9. The method of claim 1, wherein said modified features are represented by a single polarity of dots.

10. The method of claim 1, wherein said modified features are displayed as a bipolar representation.

11. The method of claim 1, wherein said natural scene is a low light environment and wherein, further, said obtained image is an infrared or a radar image.

12. The method of claim 1, further comprising changing the magnification of said image.

13. The method of claim 12, wherein the magnification of said image is changed before said extracting step.

14. The method of claim 12, wherein the magnification of said image is changed after said extracting step.

15. The method of claim 1, wherein the extracting step includes:

(a) applying a plurality of filters having different center frequencies to the image to obtain a plurality of filtered images,

(b) assigning luminance scales to pixels of said filtered images by depicting a pixel by a light scale when absolute amplitude of said pixel is above a selected threshold and said pixel has a positive amplitude, depicting a pixel by a dark scale when absolute amplitude of said pixel is above said selected threshold and said pixel has a negative amplitude, and depicting the remaining pixels by a gray scale, and

(c) constructing contour features of the image by depicting a pixel of the image by a light scale if said pixel is represented by a light scale in all of said assigned images, depicting a pixel by a dark scale if said pixel is represented by a dark scale in all of said assigned images, and depicting the remaining pixels by a gray scale.

16. The method of claim 15, wherein said step of applying a plurality of filters includes selecting said plurality of filters to comprise oriented filters.

17. The method of claim 15, wherein said step of applying a plurality of filters includes selecting said plurality of filters to comprise spatial domain filters.

18. The method of claim 17, wherein said step of applying a plurality of filters includes selecting said oriented filters to comprise spatial filters whose angular profiles are smoothed by a Gaussian multiplier.

19. The method of claim 15, wherein said step of applying a plurality of filters includes selecting said filters to comprise Discrete Fourier Transforms.

20. The method of claim 15, wherein said step of applying a plurality of filters includes selecting said filters to comprise a wavelet transform.

21. The method of claim 1, further including after said manipulating step minifying said extracted features.

22. The method of claim 9 further including the step of connecting proximal dots to form a contour image.

23. The method of claim 10 further including the step of connecting proximal dots to form a contour image.

24. The method of claim 13 wherein the change in magnification is to minify said image.

25. The method of claim 14 wherein the change in magnification is to minify said image.

26. The method of claim 1 wherein said projecting step includes encoding transmitted television images using an enhancement signal by supplanting an image signal with said modified features.

27. The method of claim 26 further including the step of decoding said enhancement signal and displaying said supplanted image with said modified features.

28. A method for real-time modification of a natural scene for a human observer, said method comprising the steps of:

obtaining an image of said natural scene;

extracting features of said image selected from the group consisting of local maximum luminance, local minimum luminance and transitions between regions of varying luminance;

manipulating said extracted features to obtain modified features, wherein said modified features are represented by a single polarity of dots or said modified features are displayed as a bipolar representation; and

projecting said modified features onto a semi-transparent screen disposed in front of an eye of said observer to enable simultaneous viewing of both the natural scene and the modified features by said observer.