Papers by Keyword: Point Spread Function

Abstract: Super-resolution image restoration technique can certainly increase the resolution of the obtained images without altering the system hardware conditions, which has become a research hotspot in the fields of remote sensing, military surveillance, public safety and medical imaging. The spatial domain algorithm has been studied widely and deeply, but it still has shortcomings and limitations. This paper studies the image degradation mechanism, establishes a precise image degradation process model, proposes an improved hybrid MAP-POCS restoration algorithm with using the Huber-Markov random field model as the priori probability model, which adds the convex sets constraints to the MAP estimation process and uses the peak signal to noise ratio (PSNR) to evaluate the recovery image quality. The simulation results show that the improved hybrid algorithm combines the only solution solving feature and noise reduction ability of the MAP method and strong prior knowledge utilized feature and flexibility of the POCS method, effectively ensures the convergence stability of the restoration and maintains the edge details of the restored image, enhances the effect of the super-resolution restoration.

Abstract: according to the real motion blur image restoration problems, analyze the difference between the image features and Simulation of real blurred images, this paper proposes a method that applied to real image degradation parameter estimation. First calculate the degraded image using cepstrum, taking the cepstrum to binary image using absolute value of minimum gray as the threshold, and then remove the center cross bright line; and then use formula of point to line to calculate the distance of bright fringe direction of binary image, that is direction of motion blur; the direction of motion blur is rotated to the horizontal direction by the degraded image center of rotation axis, divided the autocorrelation method to calculate fuzzy scale. To estimate the point spread function is take into the Wiener filtering algorithm to recover images, image restoration effect prove that parameter estimation results are correct.

Abstract: To meet the performance test for the confocal laser scanning microscope (CLSM) accurately in some specific application occasions, the spatial resolution imaging principle of confocal laser scanning microscope was analyzed theoretically. And the micron line spacing as the measurement standard has tried to investigate the lateral resolution of CLSM in experiment. The value range of the lateral resolution was calculated by the fluctuation state of the output light intensity signal when there is the lateral movement between the objective with sample. At the same time, some reasons for spatial resolution are also been evaluated in theory. Experiments demonstrate that if the value of the line spacing standard is closer to the spatial resolution of CLSM, the standard can be utilized to test the spatial resolution. So we can use a a series of lines spacing standards with different lines spacing values to test the serial effective resolution. And in our experiment, we only measured line spacing standard with 8μm line width and 100μm line pitch with many times by CLSM, and the spatial resolution of the CLSM is obtained about more minimal than 0.3μm by the scanning curves.

Abstract: The RL(Richardson-Lucy) algorithm is an important method for restoration of turbulence-degraded images. However, the shortcoming of this method is that it tends to amplify the noise and exsits excessive smoothing in the iterative procedure. This paper discusses the RL algorithm and its improving methods focusing on turbulence-degraded images restoration.Firstly, a short exposure atmospheric turbulence-degraded model is established and a numerical computing method is proposed for random phase screen. Secondly, the essential principle and computational formula are deduced. To restore the object image effectively from the turbulence-degraded image, a new double-circulation iterative Richardson-Lucy restoration algorithm using TV-regularized method is proposed. This new algorithm introduces the total variation restraint and estimates the object image and the point spread function based on the inner and outer double-circulation iteration, which can use the inherent relation between the object image and the point spread function adequately. Simulation experiments show that the proposed algorithm can effectively preserve the details and edges of the image and its restoration effect is obviously better than the traditional RL algorithm.

Abstract: The requirement of the accuracy of microscopic measurements becomes more and more high, and traditional methods have been unable to meet the demands. Digital image deconvolution techniques are applied in microscopic measurement. By fabricating a pointolite, the point spread function of the optical system is measured, and then the geometric blurring in traditional microscopy is removed by using the maximum likelihood estimation algorithms and iteration threshold segmentation algorithms. The technique is applied to measure the total content of perlite and spheroidal graphite in spheroidal graphite iron accurately and easily, and then to measure the area of a scratch scaled in 10 microns on a medical department of orthopedics plates. The technique makes great sense in the development of corresponding measurement.

Abstract: The restore algorithm of the image blurred by motion is proposed, and a mathematical model based on motion blur system is eomtrueted£®The Point spread function of the motion blur is given According to the characteristics of blurred images the parameters of point spread function are estimated ,and three methods are introduced for image restoration. The three methods are inverse filtering of image restoration, Lucy-Richardson image restoration and Wiener image restoration. The principles of the three image restoration methods are analyzed. The motion blurred image restoration experiment is made. The results show that the visibility of the image is improved, and the image restoration is more stable.

Abstract: The restore algorithm of the image blurred by motion is proposed, and a mathematical model based on motion blur system is eomtrueted£®The Point spread function of the motion blur is given£®According to the characteristics of blurred images£¬the parameters of point spread function are estimated ,and three methods are introduced for image restoration. The three methods are inverse filtering of image restoration,Lucy-Richardson image restoration and Wiener image restoration.The principles of the three image restoration methods are analyzed. The motion blurred image restoration experiment is made. The results show that the visibility of the image is improved ,and the image restoration is more stable.

Abstract: Photogrammetric techniques have demonstrated their suitability for monitoring static structural tests. Advantages include scalability, reduced cost, and three dimensional monitoring of very high numbers of points without direct contact with the test element. Commercial measuring instruments now exist which use this approach. Dynamic testing is becoming a convenient approach for long-term structural health monitoring. If image based methods could be applied to the dynamic case, then the above advantages could prove beneficial. Past work has been successful where the vibration has either large amplitude or low frequency, as even specialist imaging sensors are limited by an inherent compromise between image resolution and imaging frequency. Judgement in sensor selection is therefore critical. Monitoring of structures in real-time is possible only at a reduced resolution, and although imaging and computer processing hardware continuously improves, so the accuracy demands of researchers and engineers increase. A new approach to measuring vibration is introduced here, whereby a long-exposure photograph is used to capture a blurred image of the vibrating structure. The high resolution blurred image showing the whole vibration interval is measured with no need for high-speed imaging. Results are presented for a series of small-scale laboratory models, as well as a larger scale test, which demonstrate the flexibility of the proposed technique. Different image processing strategies are presented and compared, as well as the effects of exposure, aperture and sensitivity selection. Image processing time appears much faster, increasing suitability for real-time monitoring.

Abstract: Focal length of lens is an important parameter to determine the relationship between objective and image. It must be measured accurately. The traditional method of using optical bench to measure the focal length of lens has big man-made errors. So we used linear array CCD camera instead of eyes as the receiver to measure the focal length of lens in this paper. Based on the theory of point spread function, it firstly determined the evaluation function of focal plane. With the threshold method, it determined the location coordinate of sharp signal. Then it proved the feasibility of this scheme through experiment. Finally we compared the experimental data obtained with this method with the experimental data obtained with traditional method, which showed that it was more accurate to measure the focal length of lens with this method.

Abstract: In order to study the influence of surface error on optical properties for optical part after machining, this paper takes a piece of ring curved lens with aperture D=2mm as an example. When analyzing the influence of surface error on optical properties, it employs the evaluation indexes i.e. wavefront aberration, point spread function and modulation transfer function. The study results show that with the increment of surface error, the value of wavefront aberration increases. Plus, the light of outer loop on the image plane is more obvious and its energy increases, however, the energy in the center range decreases. Moreover, the capacity of information storage decreases and also the image quality decreases.