Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi
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Sheng Wu Yi Xue Gong Cheng Xue Za Zhi · Dec 2008
[Segmentation of medical images based on dyadic wavelet transform and active contour model].
The interference of noise and the weak edge characteristic of symptom information on medical images prevent the traditional methods of segmentation from having good effects. In this paper is proposed a boundary detection method of focus which is based on dyadic wavelet transform and active contour model. In this method, the true edge points are detected by dyadic wavelet transform and linked by improved fast active contour model algorithm. The result of experiment on MRI of brain shows that the method can remove the influence of noise effective and detect the contour of brain tumor actually.
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Sheng Wu Yi Xue Gong Cheng Xue Za Zhi · Dec 2008
[MR brain image segmentation based on modified fuzzy C-means clustering using fuzzy GIbbs random field].
A modified algorithm using fuzzy Gibbs random field model and fuzzy c-means (FCM) clustering is proposed for segmentation of Magnetic resonance(MR) brain images. Spatial constraints using the definitions of homogeneity of cliques and fuzzy Gibbs clique potential are introduced in this algorithm. ⋯ This algorithm can improve the performance of corresponding traditional one by modifying the original intensity based segmentation model. Experiments on synthetic images and MR phantoms show the validation of the proposed algorithm, which is usually a better alternative for segmenting medical MR images corrupted by noise.
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Sheng Wu Yi Xue Gong Cheng Xue Za Zhi · Oct 2008
[Measuring the contrast resolution limits of human vision based on the modern digital image processing].
In the literatures on the human vision physiology and physics, there were reports about space resolution limit of 1' visual angle, frequency resolution limit of 5 nm and time resolution limit of 0.1" of human vision. However, there has been no report about the contrast resolution limit of human vision,especially the report of measuring method and result about the contrast resolution limit of human vision based on the modern digital image processing. ⋯ The function relationships of contrast resolution limit varying with background gray in a photopic or a scotopic sights were illuminated respectively. It can be expected that such investigations with regard to human vision will establish the physiological foundation of the theories and techniques in hiding bodies and hiding figures (stealth), in anti-hiding bodies and anti-hiding figures, in the night vision system independent of infrared, as well as in their relative industries.
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Sheng Wu Yi Xue Gong Cheng Xue Za Zhi · Oct 2008
[Analysis and research of brain-computer interface experiments for imaging left-right hands movement].
This is a research carried out to explore a pragmatic way of BCI based imaging movement, i. e. to extract the feature of EEG for reflecting different thinking by searching suitable methods of signal extraction and recognition algorithm processing, to boost the recognition rate of communication for BCI system, and finally to establish a substantial theory and experimental support for BCI application. In this paper, different mental tasks for imaging left-right hands movement from 6 subjects were studied in three different time sections (hint keying at 2s, 1s and 0s after appearance of arrow). Then we used wavelet analysis and Feed-forward Back-propagation Neural Network (BP-NN) method for processing and analyzing the experimental data of off-line. ⋯ There were obviously different features for imaging left-right hands movement about 0.5-1s before actual movement; these features displayed significant difference. We got higher recognition rate of communication under the hint keying at about 1s after the appearance of arrow. These showed the feasibility of using the feature signals extracted from the project as the external control signals for BCI system, and demon strated that the project provided new ideas and methods for feature extraction and classification of mental tasks for BCI.
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Sheng Wu Yi Xue Gong Cheng Xue Za Zhi · Aug 2008
Review[Review of visual prosthesis (II)--cortical visual prosthesis, optic nerve prosthesis and vision substitution devices].
Cortical visual prosthesis, optic nerve visual prosthesis and vision substitution devices are alternative ways for repairing the visual impairment in case of optic nerve injury, retina lose or blindness without fully developed central visual system. This article is a state-of-art review of the principles, technical details and the limitations of different types of prostheses beyond the retinal prosthesis.