Mr. Lei Zhang Profile

Lei Zhang

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Publications (2)

Proceedings Article | 25 November 2009 Paper

3D reconstruction based on wavelet pyramid image fusion algorithm for digital microscope

Lei Zhang, Peng Liu, Yuling Liu, Feihong Yu

Proceedings Volume 7513, 751312 (2009) https://doi.org/10.1117/12.837397

KEYWORDS: Image fusion, Reconstruction algorithms, 3D modeling, Image processing, Wavelets, Microscopes, 3D image processing, 3D image reconstruction, Digital imaging, Discrete wavelet transforms

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Optical microscopy is an important technique in petrological and biological. However, because of the limited focus depth of a traditional optical microscope, 3D objects can't be observed with all its information in one scene. The commonly used method to solve this problem is to use a digital microscope to collect a sequence of multi-focus images with a constant change of the focal length and then get the final sharp image by fusing the images. Wavelet pyramid algorithm is one of the commonly used fusion algorithms and has a good performance. In this paper, a novel 3D reconstruction algorithm is presented based on the wavelet pyramid image fusion algorithm. First, a sequence of multi-focus images is collected with a digital microscope and then the images are fused with the wavelet pyramid fusion algorithm. After that, the deviation between the fused image and each of the original multi-focus images are calculated pixel by pixel. For convenience, the absolute value of the deviation is calculated. The smaller the deviation, the closer the corresponding pixel to the focal plane and vice versa. Thus a 3D deviation matrix is obtained. For each pixel position (x, y), the z index of the smallest deviation value in the third direction of the deviation matrix is considered the pixel's height index. A complete height index map is obtained by selecting the indices of these smallest deviation values. In order to eliminate the noise effect, a median filter is applied to the height index map. The height index map times the height factor (the unit step length along the optical axis when collecting the multi-focus images) is the object's actual height map. Finally, the surface of the 3D object is reconstructed with the object's height map. In order to test the reconstruction algorithm, a dedicated high resolution Complementary Metal Oxide Semiconductor (CMOS) digital microscope is designed and fabricated to collect the multi-focus images. Experimental results show that the proposed algorithm produces a nice looking surface of a 3D object.

Proceedings Article | 6 August 2009 Paper

Real-time multi-core parallel image sharpness evaluation algorithm for high resolution CCD/CMOS based digital microscope autofocus imaging system

Lei Zhang, Peng Liu, Yu-ling Liu, Fei-hong Yu

Proceedings Volume 7384, 738415 (2009) https://doi.org/10.1117/12.835288

KEYWORDS: Image analysis, Imaging systems, Microscopes, Image resolution, Image processing, Parallel computing, Digital imaging, Evolutionary algorithms, Image acquisition, Digital image processing

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