Biomedical subjects
Publications and source records attributed to He-qin Zhou.
A wavelet threshold denoising algorithm for CR images is put forward here . A noised CR image is decomposed into wavelet coefficients, which are processed by the algorithm, and the denoised CR image is reconstructed based on the processed coefficients. Examples are too presented to demonstrate the efficiency of the algorithm on denoising and, maintaining the detail of the CR images.
Based on the theory of magnet circuits, the paper introduces the process of designing MRI (Magnetic Resonance Imaging) permanent magnet. The measurement of magnet properties is improved by simulation technology. In order to increase the magnetic field homogeneity. We have designed a shim-loop and a trapeziform shim-board to optimize the magnetic field distribution. The results of both simulation analysis and experiments show that the innovative design improves magnetic field properties significantly and the magnet structure accords with the technology requirements.
OBJECTIVE: To find a new approach to improve the uniformity of color parameters for images data of the serial sections of the human body. METHOD: An auto-color correction algorithm in the RGB color space based on a standard CMYK color chart was proposed. The gray part of the color chart was auto-segmented from every original image, and fifteen gray values were attained. The transformation function between the measured gray value and the standard gray value of the color chart and the lookup table were obtained. In RGB color space, the colors of images were corrected according to the lookup table. RESULT: The color of original Chinese Digital Human Girl No. 1 (CDH-G1) database was corrected by using the algorithm with Matlab 6.5, and it took 13.475 s to deal with one picture on a personal computer. CONCLUSION: Using the algorithm, the color of the original database is corrected automatically and quickly. The uniformity of color parameters for corrected dataset is improved.
Imaging objects are spatially encoded by gradient magnetic fields in magnetic resonance imaging systems. The eddy current caused by rapid switches of gradient fields will result in artifacts in the images. A method of eddy current compensation based on pre-emphasis of gradient current is presented in this thesis. The compensation parameters are acquired rapidly utilizing Faraday's induction theorem and data fitting method. The experiments prove that the method is efficient for reduction of the debugging time and for the improvement of the image quality.
OBJECTIVE: To describe a spatial data structure called sorted volumetric data structure which speeds up the volume rendering and will not affect image quality. METHOD: Before volume rendering we transfer each slice of volume into an array indexed by the value of voxels, element in which stores the position of each voxel. According to the opacity transfer function, we can affirm the value ranges of voxels that are non-transparent. Therefore we translate, resample and composite only the voxels in the value ranges. By marching through the sorted arrays, we locate the non-transparent voxels rapidly and skip all voxels that are transparent. The sorted data structures need not recompute whenever the opacity transfer function changes and are not restricted on the opacity transfer function. RESULT: The method presented in this paper has been implemented in a standard personal computer. The rendering time for CT head volume data is less than 1 s that is satisfied with the diagnostic purpose. CONCLUSION: The concept of proposed algorithm is simple, easy to realize and it is not recomputed whenever the opacity transfer function changes. By using the sorted volumetric data structure, we speed up the volume rendering without affecting image quality.
Objective. To design a 3D surface reconstruction algorithm capable of reconstructing 3D shapes of the organs, bones and tissues rapidly from CT or MR image on a personal computer. Method. By transforming and decomposing the projection of the discrete 3D data field into shear transformation and warp transformation, a Shear-Warp algorithm realizing the 3D reconstruction was established. The algorithm reduce the amount of computation obviously. The 3D surface was reconstructed by using the principle of the parallel projection, basing on the Shear-Warp algorithm. Shear transformation was performed on the volume data at first. Then the warped 3D surface was obtained by making a threshold in the sheared space. The brightness of the 3D surface was calculated using Phong brightness model, and the final image was generated through the Warp transformation. Result. A direct 3D surface reconstruction algorithm was established basing on a principle of projection from the Shear-Warp algorithm, which was able to display 3D surface on a personal computer rapidly. Conclusion. Compared with other surface reconstruction algorithms, the proposed algorithm has the advantages of no preprocessing, no intermediate data are generated in the reconstruction. With this new algorithm, it is possible to realize fast 3D surface rendering for medical images on a personal computer without the support of any hardware accelerator.
This paper describes the design of the printing output function for a multi-parameter patient monitor by using the graphic plot function of a Laser Printer. The ECG data are preprocessed with a notch filter and interpolation algorithm. A logical page is constructed in the extended memory for virtual page printing. This monitor is able to output a satisfied printing with ECG waveforms of high quality.