## Wavelet-Based Image Enhancement in X-Ray Imaging and Tomography

Applied Optics, Vol. 37, Issue 20, pp. 4437-4448 (1998)

http://dx.doi.org/10.1364/AO.37.004437

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### Abstract

We consider an application of the wavelet transform to image processing in x-ray imaging and three-dimensional (3-D) tomography aimed at industrial inspection. Our experimental setup works in two operational modes–digital radiography and 3-D cone-beam tomographic data acquisition. Although the x-ray images measured have a large dynamic range and good spatial resolution, their noise properties and contrast are often not optimal. To enhance the images, we suggest applying digital image processing by using wavelet-based algorithms and consider the wavelet-based multiscale edge representation in the framework of the Mallat and Zhong approach [IEEE Trans. Pattern Anal. Mach. Intell. **14,** 710 (1992)]. A contrast-enhancement method by use of equalization of the multiscale edges is suggested. Several denoising algorithms based on modifying the modulus and the phase of the multiscale gradients and several contrast-enhancement techniques applying linear and nonlinear multiscale edge stretching are described and compared by use of experimental data. We propose the use of a filter bank of wavelet-based reconstruction filters for the filtered-backprojection reconstruction algorithm. Experimental results show a considerable increase in the performance of the whole x-ray imaging system for both radiographic and tomographic modes in the case of the application of the wavelet-based image-processing algorithms.

© 1998 Optical Society of America

**OCIS Codes**

(100.2980) Image processing : Image enhancement

(100.7410) Image processing : Wavelets

(110.6960) Imaging systems : Tomography

**Citation**

Andrei V. Bronnikov and Gerrit Duifhuis, "Wavelet-Based Image Enhancement in X-Ray Imaging and Tomography," Appl. Opt. **37**, 4437-4448 (1998)

http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-37-20-4437

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