Robust infrared small target detection in infrared warning and defending system is a challenging task due to the low signal-to-clutter ratios and complex background. Motivated by human vision system, we proposed a scale adaptive patch-based contrast measure(SPCM) method for infrared small target detection. At the first stage, a patch-based contrast model is established for measuring small target scale response, whose highest response corresponding to the best estimated size of the target, at the same time, filtering out some non-target areas and leave potential candidates. At the Second stage, we calculate local patch contrast at candidate regions with the estimated target scale. Utilizing the just right scale, the patch-based contrast measure could effectively suppress background clutter and extract infrared small target in single image. Finally, an improved adaptive threshold method by using statistical information of candidate target is used to segment infrared small target. In order to verify the effectiveness of the proposed approach, we compared our method with several fixed-scale and multi-scale infrared small detection algorithm. Experimental results indicate that our method is not only able to effectively estimate the actual scale of the target, but also detect weak small target accurately in heterogeneous background with low and comparable false alarm ratio, while achieving three times faster runtime performance than multi-scale algorithm.
This paper proposes a real-time FPGA-based architecture of improved ORB. It proposes a strategy of redistribution of ORB feature points, which solves the problem of sorting FAST points of the whole image by response score. Besides, a strategy for offline generation of rBrief point pair patterns is proposed, which avoids online rotation of neighborhood pixels of feature points. These two strategies greatly reduce the resource consumption and processing clock cycles of the whole architecture. What’s more, the data throughput of the feature extraction step and feature description step is maximized, and finally a completely pipeline architecture is obtained. Due to the tips for parallel processing and resource reuse, the hardware implementation of the proposed architecture costs very few resources and processing cycles. The experimental results show that this architecture can detect feature and extract descriptor from video streams of 1280x720 resolution at 161 frames per second (161 fps), and the extracted ORB features perform well.
The Accuracy of correlation filtering trackers have got great improvement because of using high dimension features, but its real-time performance became worsen. And we often have the meet of running tracker on embedding device, in this case, we need less calculation. It is all known that the model updating strategy is also important for tracking performance. The fixed learning rate model updating strategy is difficult to deal with the situation that the object changes rapidly or slowly. For the problem, a new correlation surface quality evaluation metric is proposed in this paper. Meanwhile, we consider the occlusion of the object, and propose the occlusion judgment algorithm. Finally, the learning rate of model is updated adaptively according to the change speed of the object and whether the object is occluded. We further conduct experiment on the OTB50 dataset. Experimental results show that the correlation tracker with gray feature can improve the tracking accuracy by about 3% compared with MOSSE tracker, after adopting the learning rate adaptive strategy proposed in this paper and maintain high speed on embedding device.
The high-speed railway overhead contact system is a transmission line that is erected along the high-speed railway and supplies power to the electric locomotive. Once the overhead contact system is powered off, it will directly affect the safe operation of the locomotive, with serious consequences. Insulators are the key components for regular inspection of high-speed railway overhead contact system. The common faults of insulators are damage, dirt and discharge. There are many types of components in a single image, but their shapes vary from different components. These components should be divided into normal or multiple different fault types. Usually the difference between different fault types of the same component is small. Therefore, a hierarchical coarse-to-fine strategy is proposed to address this issue. Specifically, for a trade-off between efficiency and accuracy, an efficient network is leveraged to detect the insulator in the image, and an accurate network is then utilized to identify the fault.
In image mosaicking applications, the color of images for mosaicking may be inconsistent due to different camera settings and lighting conditions. This paper proposes an effective color correction algorithm to correct the photometrical disparities. Firstly, corresponding points between two images are extracted using SIFT Flow. Secondly, the corresponding points will serve as the control points of the weighted moving least squares algorithm to correct the color of input image. This operation is conducted for each channel of input image respectively in RGB space. Finally, combining three corrected single channel image, we get the final corrected RGB image. Experimental results have shown that the proposed color correction method yields better performance than the state-of-art algorithms.
For video stabilization, the difference between original camera motion path and the optimized one is proportional to the cropping ratio and warping ratio. A good optimized path should preserve the moving tendency of the original one meanwhile the cropping ratio and warping ratio of each frame should be kept in a proper range. In this paper we use an improved warping-based motion representation model, and propose a gauss-based multi-paths optimization method to get a smoothing path and obtain a stabilized video. The proposed video stabilization method consists of two parts: camera motion path estimation and path smoothing. We estimate the perspective transform of adjacent frames according to warping-based motion representation model. It works well on some challenging videos where most previous 2D methods or 3D methods fail for lacking of long features trajectories. The multi-paths optimization method can deal well with parallax, as we calculate the space-time correlation of the adjacent grid, and then a kernel of gauss is used to weigh the motion of adjacent grid. Then the multi-paths are smoothed while minimize the crop ratio and the distortion. We test our method on a large variety of consumer videos, which have casual jitter and parallax, and achieve good results.
Discriminative correlation filters (DCF) have recently shown excellent performance in visual object tracking area. In this paper we summarize the methods of updating model filter from discriminative correlation filter (DCF) based tracking algorithms and analyzes similarities and differences among these methods. We deduce the relationship among updating coefficient in high dimension (kernel trick), updating filter in frequency domain and updating filter in spatial domain, and analyze the difference among these different ways. We also analyze the difference between the updating filter directly and updating filter’s numerator (object response power) with updating filter’s denominator (filter’s power). The experiments about comparing different updating methods and visualizing the template filters are used to prove our derivation.
KEYWORDS: Detection and tracking algorithms, Motion estimation, Video, Optical tracking, Video surveillance, Visualization, Optimal filtering, Digital image correlation and tracking
Discriminative correlation filter (DCF) based trackers have recently achieved excellent performance with great computational efficiency. However, DCF based trackers suffer boundary effects, which result in the unstable performance in challenging situations exhibiting fast motion. In this paper, we propose a novel method to mitigate this side-effect in DCF based trackers. We change the search area according to the prediction of target motion. When the object moves fast, broad search area could alleviate boundary effects and reserve the probability of locating object. When the object moves slowly, narrow search area could prevent effect of useless background information and improve computational efficiency to attain real-time performance. This strategy can impressively soothe boundary effects in situations exhibiting fast motion and motion blur, and it can be used in almost all DCF based trackers. The experiments on OTB benchmark show that the proposed framework improves the performance compared with the baseline trackers.
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