Applications In Optical Image Processing Research Articles

An Efficient and Precise Remote Sensing Optical Image Matching Technique Using Binary-Based Feature Points.

Matching local feature points is an important but crucial step for various optical image processing applications, such as image registration, image mosaicking, and structure-from-motion (SfM). Three significant issues associated with this subject have been the focus for years, including the robustness of the image features detected, the number of matches obtained, and the efficiency of the data processing. This paper proposes a systematic algorithm that incorporates the synthetic-colored enhanced accelerated binary robust invariant scalar keypoints (SC-EABRISK) method and the affine transformation with bounding box (ATBB) procedure to address these three issues. The SC-EABRISK approach selects the most representative feature points from an image and rearranges their descriptors by adding color information for more precise image matching. The ATBB procedure, meanwhile, is an outreach that implements geometric mapping to retrieve more matches from the feature points ignored during SC-EABRISK processing. The experimental results obtained using benchmark imagery datasets, close-range photos (CRPs), and aerial and satellite images indicate that the developed algorithm can perform up to 20 times faster than the previous EABRISK method, achieve thousands of matches, and improve the matching precision by more than 90%. Consequently, SC-EABRISK with the ATBB algorithm can address image matching efficiently and precisely.

Third-harmonic generation and its applications in optical image processing

We review potential applications of third-harmonic generation (THG) in polymer composites to implement optical image processing applications at the eye-safe and technologically relevant telecommunication bands. We discuss two examples, time-gated imaging through scattering media, and image recognition using Fourier-based techniques, where THG in a polymer composite offers significant advantages over typical holographic media, in that it produces signals that are non-degenerate in optical frequency and space, and allows the development of applications that are compatible with low-cost Si-based electronic components.

Image feature extraction by dynamic neural filtering and phase-only joint transform correlation

Neural network-based image processing algorithms present numerous advantages due to their supervised adjustable properties. Among various neural network architectures, dynamic neural networks, Hopfield and Cellular networks, have been found inherently suitable for filtering applications. Combining supervised and filtering features of dynamic neural networks, this paper presents dynamic neural filtering technique based on Hopfield neural network architecture. The filtering technique has also been implemented by using phase-only joint transform correlation (POJTC) for optical image processing applications. Filtering structure is basically similar to the Hopfield neural network structure except for the adjustable filter mask and 2D convolution operation instead of weight matrix operations. The dynamic neural filtering architecture has learnable properties by back-propagation learning algorithm. POJTC presents significant advantages to achieve the operation of summing the cross-correlation of bipolar data by phase-encoding bipolar data in parallel. The image feature extraction performance of the proposed optical system is reported for various image processing applications using a simulation program.

Photo-induced anisotropic photoelectric response in oriented bacteriorhodopsin films

The photo-induced anisotropic properties of the chromophore protein bacteriorhodopsin (bR) are of interest for possible applications in optical image processing and spatial filtering. Here we report experimental results on the photo-induced anisotropic photoelectric response of dried oriented bR films. A polarization dependent photovoltage is measured across an ITO/bR/ITO photodetector. The anisotropy is introduced by a 632.8 nm linearly polarized pump beam and is detected with a 594.1 nm polarized probe beam. The influence of the pump light intensity on the photovoltage anisotropy has also been investigated. A model, based on the polarization dependent photoselection of the bR molecules reasonably explains the behavior of the measured data. The observed effect can be used to construct a polarization sensitive bR-based bio-photoreceiver.

Wavelet transform-based correlator for the recognition of rotationally distorted images

A novel wavelet-based joint transform correlator (WJTC) for rotation-invariant pattern recognition and applications in optical image processing and remote sensing is investigated. First an optimal set of filter parameters and a mother wavelet filter are selected. These are used to extract features at different resolution from a set of rotationally distorted training images. Then a composite reference feature is formulated from these features for use in the WJTC. Simulation results for both noisy and noiseless environments are presented to verify the effectiveness of this technique.

Optical computing by use of photorefractive polymers

A matched-filter four-wave-mixing optical correlator was built with a photorefractive polymer as the nonlinear material. Two different time scales are important for this type of device: the time to write a grating, which is limited by the response time of the photorefractive material (~100 ms for the polymer used) and the time to diffract light from the grating, which is essentially instantaneous. For the matched-filter optical correlator we have obtained correlations comparing two 5000-pixel images, using 220-fs pulses with 5-mW average power, demonstrating that the time to compare the test image and the reference image is not limited by the relatively slow response time of the photorefractive polymer. Since the photorefractive grating is erasable the device can be reprogrammed for a different reference image in less than 1 s. The results show that photorefractive polymers can be used efficiently in optical image processing applications.

Multiple forward phase conjugate waves by degenerate four-wave mixing in Langmuir-Blodgett films with BOXCARS geometry

We present an efficient and simple way to generate multiple forward phase conjugate waves (FPCWs) by means of degenerate four-wave mixing in Langmuir-Blodgett (LB) films with BOXCARS structure. A conversion efficiency of the phase conjugate wave of about 15% was obtained in a cyanine-arachidic acid (CY-AA) complex LB film containing 100 CY-AA monolayers. This way of generating FPCWs will provide us with an efficient measure to investigate the third-order optical nonlinearities of thin films, and the FPCWs obtained here will find potential applications in optical image processing.

Speckle metrology employing LCTV spatial light modulators

Liquid crystal televisions have been employed as spatial light modulators in a variety of optical image processing applications. We have used such devices to develop techniques in speckle metrology for the electronic addition of speckle patterns and the display of speckle correlation, and also for the real-time display of object motion. Factors which affect the performance in terms of the useful working range and the accuracy of displacement measurement are discussed. Some modifications to the LCTV which should increase the potential of these devices as spatial light modulators, when used in both amplitude and phase modulation, are considered briefly.

Photorefractive materials and their applications in optical image processing

A brief review of a band transport model for the photorefractive effect is given. Distinction is made between the influence of intrinsic material dependent parameters and externally controlled parameters on the form of the optical nonlinearity. These considerations are made in the context of dynamic holographic optical processing applications. Examples of adaptive optical and Fourier-plane image processing using four-wave mixing in photorefractive bismuth silicon oxide crystals are discussed. Critical assessment is then made of the use of photorefractive materials in image cross-correlation schemes.