Zouhir Bahri
Carnegie Mellon University
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Featured researches published by Zouhir Bahri.
Applied Optics | 1989
B. V. K. Vijaya Kumar; Zouhir Bahri
We introduce the notion of optimal phase-only filters (OPOFs) that yield improved signal to noise ratios (SNRs). We illustrate the improvement in SNR resulting from the use of OPOFs with the help of several analytical examples and simulation results.
Journal of The Optical Society of America A-optics Image Science and Vision | 1988
Zouhir Bahri; B. V. K. Vijaya Kumar
A generalization of the conventional synthetic discriminant function (SDF) solution in both spatial and frequency domains is provided. It is based on the concept of the generalized inverse. The results of this generalization are shown to specialize to previous work (namely, the minimum-output-variance SDF). A link is established between the quantities characterizing the spatial-domain SDF solutions and the frequency-domain ones through the pseudo-discrete Fourier-transform operation. Several properties of the various relevant matrices are presented to provide a general framework for characterizing SDF solutions. To help to illustrate the advantages of the generalized SDF solution method, two examples of SDF’s (a phase-only and a two-level SDF) are investigated.
Applied Optics | 1989
B. V. K. Vijaya Kumar; Zouhir Bahri
An efficient algorithm for designing a ternary valued filter yielding the highest signal to noise ratio (SNR) is utlined. Numerical evaluations using the image of a tank indicate that using such a filter can provide an improvement in SNR of ~5 dB over the conventional binary phase-only filter (BPOF). This is superior to the 1-dB improvement obtained for that image by varying the threshold line angle (TLA) in filter binarization. Simulation results are presented. They agree with the numerically computed SNRs.
Applied Optics | 1988
B. V. K. Vijaya Kumar; Zouhir Bahri; Abhijit Mahalanobis
It is shown that proper selection of constraint phases in minimum variance synthetic discriminant functions can further reduce the output variance due to input noise. It is demonstrated with the help of examples that this reduction in variance can range from being negligible to being significant. The exact amount of reduction depends on the constraint magnitudes, training images, and the noise covariance matrix.
Optical Information Processing Systems and Architectures | 1990
Zouhir Bahri; B. V. K. Vijaya Kumar
Two algorithms are compared for the design of Phase-Only Synthetic Discriminant Functions. The first, known as the Successive Forcing Algorithm (SPA), uses a Gerchberg-Saxton type of iteration. The second, known as the Relaxation Algorithm (RA), was proposed recently by Jared and Ennis. Preliminary simulation results are included to facilitate a comparison between the two.
SPIE International Symposium on Optical Engineering and Industrial Sensing for Advance Manufacturing Technologies | 1989
B. V. K. Vijaya Kumar; Zouhir Bahri; Laurence G. Hassebrook
A critical review of training-image correlation-based optical pattern recognition algorithms is provided. An assessment of the advantages and limitations of these algorithms is given.
Applied Optics | 1990
Zouhir Bahri; B. V. K. Vijaya Kumar
Very efficient suboptimal algorithms for the design of phase-only filters and binary phase-only filters are presented. A reduction of 2- to 3-orders of magnitude in computer time is obtained over previous algorithms. The loss in signal-to-noise ratio is negligible (<0.001 dB).
1988 Los Angeles Symposium--O-E/LASE '88 | 1988
B. V. K. Vijaya Kumar; Zouhir Bahri
We introduce the notion of the Optimal Phase-Only Filters (OPOF) which yield higher Signal-to-Noise Ratios (SNR) compared to the conventional phase-only filters. We illustrate this improvement in SNR resulting from the use of OPOFs with the help of simulation results.
Hybrid Image and Signal Processing II | 1990
Zouhir Bahri; Bhagavatula Vijaya Kumar
A recently introduced algorithm called the Successive Forcing Algorithm (SFA) is generalized for designing Binary Phase-Only Synthetic Discriminant Functions (BPOSDFs). Preliminary simulation results obtained using this filter are presented. 1
Optics, Illumination, and Image Sensing for Machine Vision III | 1989
Zouhir Bahri; B. V. K. Vijaya Kumar
The distortion sensitivity of optimal phase-only filters (OPOFs) is assessed using simulations. The effect of detector noise on the passband of OPOFs is investigated.