Optical method and system for generating expansion coefficients for an image processing function

• US 5,454,047 A
• Filed: 01/12/1994
• Issued: 09/26/1995
• Est. Priority Date: 05/15/1992
• Status: Expired due to Term

• Current Assignee: OL Security LLC (Intellectual Ventures LLC)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Chang, David B., Shih, I-Fu
• Primary Examiner(s): Mancuso, Joseph
• Application Number:
  US08/180,394
• Time in Patent Office: 622 Days
• Field of Search: 382/31, 382/42, 364/822, 359/15, 359/19, 359/560, 359/554, 359/561
• US Class Current: 382/280
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform

Abstract

A system for optically generating expansion coefficients for an image processing function. The invention (10) includes a first optical element (18) for providing a transform of an image provided at a first image plane (16). A second optical arrangement (20) provides a product of the transform of the image and a transform of a convolving function. This product is transformed by a lens (22) to provide an image intensity distribution representative of expansion coefficients resulting from a convolution of the image by the convolving function. In a specific implementation, the convolving function is a wavelet and the intensity distribution is detected to provide the expansion coefficients.

Claims

1. A system for optically generating expansion coefficients for a wavelet representation of an image, said image comprising a series of wavelet functions, comprising:

first optical means for providing an optical representation of said image;

second optical means for Fourier transforming said optical representation of said image;

third optical means for optically providing a Fourier transform of a convolving function of said wavelet functions;

fourth optical means for providing an optical product of the Fourier transform of said image and the Fourier transform of said convolving function of said wavelet functions;

fifth optical means for optically transforming said product to provide a spatial intensity distribution representative of the expansion coefficients of said wavelet representation of said image on optical detector array, said detector array responsive to said spatial intensity distribution for generating electrical signals corresponding to said intensity distribution which are representative of the expansion coefficients of said wavelet representation of said image; and

means for storing said electrical signals as a wavelet representation of said image.

2. The invention of claim 1 wherein said first optical means includes a source of collimated energy.

3. The invention of claim 2 wherein said source of collimated energy includes a light source and a collimating first lens.

4. The invention of claim 2 wherein said first optical means incudes means for providing said optical representation of said image at a first image plane.

5. The invention of claim 4 wherein said first optical means includes a photographic plate on which said optical representation of said image is stored.

6. The invention of claim 4 wherein said second optical means includes a second lens for providing a Fourier transform of said optical representation of said image at a second image plane.

7. The invention of claim 1 wherein said third optical means comprises an optical low pass filter.

8. The invention of claim 1 wherein said third optical means includes a photographic plate on which a diffraction pattern of a round aperture is stored.

9. The invention of claim 1 wherein said fifth optical means includes a third lens for transforming the product of the transform of the image and the transform of the convolving function to provide said image intensity distribution representative of expansion coefficients resulting from a convolution of said image by said convolving function at a third image plane.

10. The invention of claim 1 wherein said detector array comprises array means for detecting the spatial intensity distribution across said third image plane.

11. The invention of claim 1 wherein said wavelet convolving function is an Airy function, and said third optical means comprises an optical low pass filter.

12. The invention of claim 11 wherein said optical low pass filter comprises a photographic plate on which is formed an optical representation of the diffraction pattern of a round aperture.

13. A method for generating expansion coefficients for a wavelet representation of an image, said image comprising a series of wavelet functions, including the steps of:

optically transforming said image;

providing an optical representation of said convolving function of said wavelet functions;

optically transforming the optical representation of said wavelet convolving function;

optically forming the product of the image transform and the wavelet convolving function transform; and

optically transforming the product of the image transform and the wavelet convolving function transform, thereby providing a spatial intensity distribution representative of the wavelet expansion coefficients of said wavelet function representation of said image;

detecting said spatial intensity distribution;

generating electrical signals corresponding to said detected spatial intensity distribution which are representative of the expansion coefficients of said wavelet representation of said image; and

storing said electrical signals as a wavelet representation of said image.