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Title
Abstract
Figures
Introduction
Experimental
Conclusion
References

Filtering Effect in Holographic Image Processing

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Abstract

The most popular application of holography is using the technique to make three-dimensional images. This paper describes an algorithm for computationally generating holograms along with methods to fabricate the hologram. The phrase, “digital holography", is common place in the optics community; it describes the methods used to reconstruct holographic images from physically recorded holograms as well as the methods used to construct holograms from virtual objects using a computer. In fact we have the ability to create digital holograms from imaginary objects and then recreate the image of those objects using the same digital holograms, the entire process performed on a single computer. A computer simulation technique for generating Fourier holograms using the Fraunhoffer diffraction formula is applied. These generated Fourier holograms were analyzed for experimental reconstruction. A detailed analysis was done on the computation and numerical reconstruction. Filtering technique was used to analyze its feasibility to be used in image processing. Corresponding reconstructions were verified by MATLAB for computer simulation. The algorithm of the MATLAB program is discussed. Using this technique, computer generated holograms can be of great use in image processing field.

Figures (4)
tty ULY te fivivyiGee tyyyuiMitty Qi $UOuiity vIVYYYY At the fundamental level, the difference between a hologram and a conventional photograph is that conventional photography A hologram is a recording of the optical interference pattern that forms at the intersection of two coherent optical beams [3] Typically, light from a single laser is split into two paths, the signal path and the reference path. Figure-1 shows this holographi recording arrangement. The beam that propagates along the signal path carries information, whereas the reference is designed to bi simple to reproduce. A common reference beam is a plane wave: a light beam that propagates without converging or diverging. Th two paths are overlapped on the holographic medium and the interference pattern between the two beams is recorded.
tty ULY te fivivyiGee tyyyuiMitty Qi $UOuiity vIVYYYY At the fundamental level, the difference between a hologram and a conventional photograph is that conventional photography A hologram is a recording of the optical interference pattern that forms at the intersection of two coherent optical beams [3] Typically, light from a single laser is split into two paths, the signal path and the reference path. Figure-1 shows this holographi recording arrangement. The beam that propagates along the signal path carries information, whereas the reference is designed to bi simple to reproduce. A common reference beam is a plane wave: a light beam that propagates without converging or diverging. Th two paths are overlapped on the holographic medium and the interference pattern between the two beams is recorded.
In signal processing, particularly digital image processing, filtering has got significant effect on image quality [5]. A holographic image doesn’t give out any meaningful image visually. But reconstructed image from the holographic image doesn’t appear exactly as According to scalar diffraction theory, the emanating wavefronts are spherical. The scalar diffraction theory at the end of Fresnel approximation reshapes the spherical wavefronts to parabolic wavefronts. Since the parabolic approximation is valid only for small diffraction angles this approximation is also called as paraxial approximation. The far field approximation of Fresnel diffraction formula yields the Fraunhoffer diffraction formula [4]. The Fraunhoffer diffraction formula is the Fourier transform of the aperture distribution. This formula greatly simplifies the calculations compared to Huygen — Fresnel diffraction formula. The simulation is employed using a simple algorithm in MATLAB language. The Fresnel diffraction formula is given by
In signal processing, particularly digital image processing, filtering has got significant effect on image quality [5]. A holographic image doesn’t give out any meaningful image visually. But reconstructed image from the holographic image doesn’t appear exactly as According to scalar diffraction theory, the emanating wavefronts are spherical. The scalar diffraction theory at the end of Fresnel approximation reshapes the spherical wavefronts to parabolic wavefronts. Since the parabolic approximation is valid only for small diffraction angles this approximation is also called as paraxial approximation. The far field approximation of Fresnel diffraction formula yields the Fraunhoffer diffraction formula [4]. The Fraunhoffer diffraction formula is the Fourier transform of the aperture distribution. This formula greatly simplifies the calculations compared to Huygen — Fresnel diffraction formula. The simulation is employed using a simple algorithm in MATLAB language. The Fresnel diffraction formula is given by
The quality of reconstructed image with respect to original image is visible from Figure - 2. Low pass filtering effect and high pass filtering effect on reconstructed image with different filtering level are shown in Figure - 2 and Figure - 3 respectively. The filtered images vary depending upon the filtering level applied on reconstructed holographic image which is evident from the properties discussed [7, 8].
The quality of reconstructed image with respect to original image is visible from Figure - 2. Low pass filtering effect and high pass filtering effect on reconstructed image with different filtering level are shown in Figure - 2 and Figure - 3 respectively. The filtered images vary depending upon the filtering level applied on reconstructed holographic image which is evident from the properties discussed [7, 8].
It is observed from the above result that reconstructed image from its hologram when low pass filtered, gives out blurring effect and sharp edges are minimized. A gain, reconstructed image from its hologram when high pass filtered, gives out reverse color effect.
It is observed from the above result that reconstructed image from its hologram when low pass filtered, gives out blurring effect and sharp edges are minimized. A gain, reconstructed image from its hologram when high pass filtered, gives out reverse color effect.

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References (6)

  1. Tung H. Jeong "Basic Principles and Applications of Holography", Lake Forest College,Lake Forest, llinois; Fundamentals Of Photonics, Module 1.10,SPIE Digital Library
  2. J.W.Goodman," Introduction to Fourier Optics", 2nd ed., The McGraw-Hill Companies, Inc., 1996
  3. Ferdous Ahmed and 2 Md. Sultan Mahmud "Fourier Optics and Computer Generated Hologram" (Submitted for publication in IJCSE)
  4. Digital Signal Processing, by J.S.Chitode, Technical Publications, 2008, ISBN 978-81-8431-346-8, 4 -70
  5. A. Umnov, A. Nasonov, A. Krylov, Ding Yong. "Sparse method for ringing artifact detection" // In: Proceedings of International Conference on Signal Processing (ICSP2014). IEEE, Hangzou, China, 2014, pp. 662-667.
  6. Ferdous Ahmed and 2 Md. Sultan Mahmud "Ringing Effect in Holographic Image Processing" (Submitted for publication in IJAMS)

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