Abstract: A method and apparatus of encrypting optical images using binarization or phase only information is presented with a number of ways to secure the image also being provided. An image to be encrypted is first multiplied by a random phase function. The Fourier transform of the product of the image and the random phase function is then multiplied by another random phase function in the Fourier (or Fresnel) domain. Taking the inverse Fourier (or Fresnel) transform, an encrypted image in the output plane is obtained. Alternatively, the image to be encrypted can be phase encoded and then encrypted to provide an extra level or security. The image can be secured using one key in the Fourier or Fresnel domain followed by phase extraction. This encrypted image may then binarized, which may include binarizing the phase-only part of the encrypted image. The use of binarization enables ease of implementation and data compression while still providing recovery of images having good quality.

Abstract: A method and system for performing three-dimensional pattern recognition by use of digital holography is disclosed. The complex amplitude distribution generated by an object is recorded by phase-shifting interferometry. The digital hologram contains information about the objects shape, location, and orientation. This information allows one to perform multi-dimensional pattern-recognition methods with a high degree of discrimination and to measure three-dimensional orientation changes.

Abstract: The present invention describes an ultrafast secure data communication system that can link remote users to an encrypted database with holographic-stored data and a high security and ultrafast transfer rate.

Abstract: A computer-based three-dimensional image reconstruction method and system are presented. An elemental image array of a three-dimensional object is formed by a micro-lens array, and recorded by a CCD camera. Three-dimensional images are reconstructed by extracting pixels periodically from the elemental image array using a computer. Images viewed from an arbitrary angle can be retrieved by shifting which pixels are to be extracted. Image processing methods can be used to enhance the reconstructed image. Further, the digitally reconstructed images can be sent via a network. A system for imaging a three-dimensional object includes a micro-lens array that generates an elemental image array. The elemental image array is detected by a CCD camera to generate digitized image information. A computer processes the digitized image information to reconstruct an image of the three-dimensional object.

Abstract: A method and apparatus of encrypting optical images and storing these images in memory using random phase encoding is presented. The encryption technique uses random phase encoding in both the input plane and the Fourier plane. Each image is encrypted and can be read out by a unique code or a universal code. The image to be encrypted is first multiplied by a random phase function. The Fourier transform of the product of the image and the random phase function is then multiplied by another random phase function in the Fourier domain. Taking the inverse Fourier transform, an encrypted image in the output plane is obtained. Each encrypted image can be stored in optical memory. The encryption process of the present invention can be done optically or electronically with one or two dimensional functions for encryption. Further, the image can be phase encoded (optically or digitally) prior to the encryption process, with a phase reading technique employed to obtain the original decrypted image.

Abstract: A method and apparatus of encrypting optical images and storing these images in memory using random phase encoding is presented. The encryption technique uses random phase encoding in both the input plane and the Fourier plane. Each image is encrypted and can be read out by a unique code or a universal code. The image to be encrypted is first multiplied by a random phase function. The Fourier transform of the product of the image and the random phase function is then multiplied by another random phase function in the Fourier domain. Taking the inverse Fourier transform, an encrypted image in the output plane is obtained. Each encrypted image can be stored in optical memory. The encryption process of the present invention can be done optically or electronically with one or two dimensional functions for encryption. Further, the image can be phase encoded (optically or digitally) prior to the encryption process, with a phase reading technique employed to obtain the original decrypted image.

Abstract: A method of verifying the authenticity of an object is disclosed employing a spatial integrating optical correlator. An unreadable and hence non-counterfeitable mask (e.g., a. complex mask or a phase mask) is coupled to the object and the optical correlator compares the mask with a reference mask on which it is scanned over. The correlator produces a correlation spot or image having an intensity which exceeds a given level if the mask is genuine. An alternate embodiment includes a fingerprint or other personalized pattern bonded to the mask, and the fingerprint or other personalized pattern on the card is compared to a reference fingerprint or other personalized pattern of the card holder for added security.

Abstract: A joint Fourier transform optical correlator is disclosed which can have varying degrees of nonlinearity and yet employ a readily available binary spatial light modulator for producing the correlation output light signal in conjunction with a Fourier transform lens. The nonlinearly transformed joint power spectrum is binarized utilizing a multiple level threshold function which can vary from one pixel to the next.

Abstract: A method and apparatus for implementation of neural networks for face recognition is presented. A nonlinear filter or a nonlinear joint transform correlator (JTC) employs a supervised perceptron learning algorithm in a two-layer neural network for real-time face recognition. The nonlinear filter is generally implemented electronically, while the nonlinear joint transform correlator is generally implemented optically. The system implements perception learning to train with a sequence of facial images and then classifies a distorted input image in real-time. Computer simulations and optical experimental results show that the system can identify the input with the probability of error less than 3%. By using time multiplexing of the input image under investigation, that is, using more than one input image, the probability of error for classification can be reduced to zero.

Abstract: A method of verifying the authenticity of an object is disclosed preferrably employing a joint transform coherent optical processor. An unreadable and hence non-counterfeitable phase mask is coupled to the object and the optical processor compares the phase mask with a reference phase mask having the same phase code thereon. The processor produces a correlation spot having an intensity which exceeds a given level if the phase mask is genuine. A highly secure ID or credit card also carries a fingerprint bonded to the phase mask, and the fingerprint on the card is compared to a reference fingerprint of the card holder for added security.

Abstract: A joint transform optical correlator is disclosed having an optical path length adjustment technique for causing a first optical path length between the reference image plane and the first Fourier transform lens to differ from a second optical path length between the input image plane and the first Fourier transform lens by an amount whereby the second Fourier transform lens separates the desired cross-correlation signals from the undesired signals to enhance the performance and reliability of the correlator.

Abstract: In a nonlinear joint transform image correlator, the Fourier transform interference intensity is nonlinearly transformed to provide higher correlation peak intensity and a better defined correlation spot. The correlation signals are determined, for example, in terms of nonlinear characteristics of a spatial light modulator (SLM) at the Fourier plane. The correct phase information of the correlation signal is recovered from the first-order harmonic of the nonlinearly transformed interference intensity, and various types of autocorrelation signals can be produced simply by varying the severity of the nonlinearity and without the need to synthesize specific matched filters. For example, the autocorrelation signal produced by a phase-only matched filter can be obtained by selecting the appropriate nonlinearity.

Abstract: A logarithmic/exponential nonlinear joint transform processor performs image deconvolution and is used to restore smeared or out of the focus degraded images. The correct Fourier phase of the original signal is restored in the joint power spectrum of the smeared image and the smearing function. The correct Fourier amplitude of the original signal is restored by essentially dividing out the Fourier amplitude of the smearing function from the joint power spectrum. The division is achieved by subtracting the log.sub.e of the power spectrum of the smearing function from the log.sub.e of the joint power spectrum followed by an exponential nonlinearity.

Abstract: The present invention is a nonlinear joint transform image correlator which employs a spatial modulator operating in a binary mode at the Fourier plane. The reference and input images are illuminated by a coherent light at the object plane of a Fourier transform lens system. A image detection device, such as a charge coupled device, is disposed at the Fourier plane of this Fourier transform lens system. A thresholding network detects the median intensity level of the imaging cells of the charge coupled device at the Fourier plane and binarizes the Fourier transform interference intensity. The correlation output is formed by an inverse Fourier transform of this binarized Fourier transform interference intensity. In the preferred embodiment this is achieved via a second Fourier transform lens system. This binary data is then applied to spatial light modulator device operating in a binary mode located at the object plane of a second Fourier transform lens system.