No abstract

The appearance of retinal blood vessels is an important diagnostic indicator of serious disease, such as hypertension, diabetes, cardiovascular disease, and stroke. Automatic segmentation of the retinal vasculature is a primary step towards automatic assessment of the retinal blood vessel features. This paper presents an automated method for the enhancement and segmentation of blood vessels in fundus images. To decrease the influence of the optic disk, and emphasize the vessels for each retinal image, a multidirectional morphological top-hat transform with rotating structuring elements is first applied to the background homogenized retinal image. Then, an improved multiscale line detector is presented to produce a vessel response image, and yield the retinal blood vessel tree for each retinal image. Since different line detectors at varying scales have different line responses in the multiscale detector, the line detectors with longer length produce more vessel responses than the ones with shorter length; the improved multiscale detector combines all the responses at different scales by setting different weights for each scale. The methodology is evaluated on two publicly available databases, DRIVE and STARE. Experimental results demonstrate an excellent performance that approximates the average accuracy of a human observer. Moreover, the method is simple, fast, and robust to noise, so it is suitable for being integrated into a computer-assisted diagnostic system for ophthalmic disorders. Category: Smart and intelligent computing

Two methods based on headspace single drop microextraction (HS-SDME) and headspace hollow fiber liquid phase microextraction (HS-HF-LPME) were developed and critically compared with HPLC-UV determination of phenols (including phenol (Ph), 2-chlorophenol (CP), 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP)) in this paper. The significant parameters affecting the extraction efficiency of the target analytes in both extraction modes were studied and the optimal extraction conditions were established. Under the optimal conditions, the detection limits (S/N = 3) for Ph, CP, DCP and TCP obtained by HS-SDME-HPLC-UV and HS-HF-LPME-HPLC-UV were 2.1, 0.2, 0.8,1.1 ng/mL and 4.2, 0.4, 0.4, 0.4 ng/mL with enrichment factors of 15.8, 198.9, 159.7, 194.8 and 9.2, 149.9, 301.9, 411.1, respectively. The RSDs obtained by HS-SDME-HPLC-UV and HS-HF-LPME-HPLC-UV were 3.7, 4.0, 9.8, 6.7% and 6.3, 3.6, 3.1, 4.8% for Ph, CP, DCP and TCP, respectively. Both extraction modes have a comparable analytical performance, but HS-HF-LPME was more robust than HS-SDME, while HS-SDME was simpler than HS-HF-LPME. The two headspace microextraction modes were applied for HPLC-UV determination of target phenols in water, honey and toner samples, and the determined values obtained by both techniques were in good agreement with each other.

The alignment problem of a rotating optical measurement system composed of a charge-coupled device (CCD) camera and a turntable is discussed. The motion trajectory model of the optical center (or projection center in the computer vision) of a camera rotating with the rotating device is established. A method based on camera calibration with a two-dimensional target is proposed to calculate the positions of the optical center when the camera is rotated by the turntable. An auxiliary coordinate system is introduced to adjust the external parameter matrix of the camera to map the optical centers on a special fictitious plane. The center of the turntable and the distance between the optical center and the rotation center can be accurately calculated by the least square planar circle fitting method. Lastly, the coordinates of the rotation center and the optical centers are used to provide guidance for the installation of a camera in a rotation measurement system. Simulations and experiments verify the feasibility of the proposed method.

In this paper, a fast rotary mechanical projector (RMP) is designed and manufactured for high-speed 3D shape measurement. Compared with the common high-speed projectors, RMP has a good performance in high-speed projection, which can obtain high quality projected fringes with shorter camera exposure time by using the error diffusion binary coding method and chrome plating technology. The magnitude, acceptability of systemic projection error is analyzed and quantified in detail. For the quantified error, the probability distribution function (PDF) algorithm is introduced to correct the error. Corrected projection error is reduced to more than one third of the original error. Subsequently, a monocular measurement system composed of the RMP and a single camera is constructed. The combination of the RMP device and PDF algorithm ensure the accuracy of a corresponding 3D shape measurement system. Experiments have demonstrated that the proposed solution has a good performance for the 3D measurement of high-speed scenes.