Dongming Lu

High resolution x-ray medical sequential image acquisition and processing system based on PCI interface

In the field of medical application, it is of great importance to adopt digital image processing technique. Based on the characteristics of medical image, we introduced the digital image processing method to the X-ray imaging system, and developed a high resolution x-ray medical sequential image acquisition and processing system that employs image enhancer and CCD. This system consists of three basic modules, namely sequential image acquisition, data transfer and system control, and image processing. Under the control of FPGA (Field Programmable Gate Array), images acquired by the front-end circuit are transmitted to a PC through high speed PCI bus, and then optimized by the image processing program. The software kits, which include PCI Device Driver and Image Processing Package, are developed with Visual C++ Language based on Windows OS. In this paper, we present a general introduction to the principle and the operating procedure of X-ray Sequential Image Acquisition and Processing System, with special emphasis on the key issues of the hardware design. In addition, the context, principle, status quo and the digitizing trend of X-ray Imaging are explained succinctly. Finally, the preliminary experimental results are shown to demonstrate that the system is capable of achieving high quality X-ray sequential images.

Research on active polarization-based target detection on sea surface

Since the polarization image contains abundant information of the object, the detecting ability of imaging system would be improved via observing the polarization features of this object. On the basis of analysis to the polarization characteristics, the active polarized imaging method is introduced in this paper, and active polarized imaging platform is built. Through this system, 3 typical samples of aluminum, iron with yellow coating, iron with green coating are adopted to simulate different objects on the sea. By measuring the parameters of amplitude ratio P, phase retardation θ, and completely depolarized coefficient ωd on the platform, which stand for the surface property of the material, we can testify the accuracy of the idea. The experiments result shows that the measured P and θ values are consistent with Fresnel equations, while for ωd , the value of seawater differs from that of the other two coating samples dramatically. As a result, it is feasible to discriminate coating target on the sea by measuring the depolarization characteristics.

Extrinsic calibration and usage of a single-point laser rangefinder and single camera

Laser and visual imagery have been broadly utilized in computer vision and mobile robotics applications because these sensors provide complementary information. So we focus attention on the fusion of 1-D laser rangefinder and camera. However, finding the transformation between the camera and the 1-D laser rangefinder is the first necessary step for the fusion of information. Many algorithms have been proposed to calibrate camera and 2-D or 3-D laser rangefinder, but few methods for 1-D laser rangefinder. In this paper, we propose a robust extrinsic calibration algorithm that is implemented easily and has small calibration error. Due to the 1-D laser rangefinder only returns a data in one dimension direction, it is difficult to build geometric constraint equations like 2-D laser rangefinder. So we are no longer constrained to build constraint equations to finish calibration. Due to the spot of the single-point laser rangefinder we commonly use is mostly invisible, we can determine the full calibration even without observing the laser rangefinder observation point in the camera image. We evaluate the proposed method demonstrating the efficiency and good behavior under noise. Finally we calibrate the installation error of camera utilizing the calibration result.