This paper presents a novel comparative study between two prominent compressed sensing algorithms - Orthogonal Matching Pursuit (OMP) and Iterative Hard Thresholding (IHT) - within the context of digital holography, s...
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ISBN:
(纸本)9781510673151;9781510673144
This paper presents a novel comparative study between two prominent compressed sensing algorithms - Orthogonal Matching Pursuit (OMP) and Iterative Hard Thresholding (IHT) - within the context of digital holography, specifically focusing on their efficacy in handling phase discontinuities. Previous research has predominantly centered on Gibbs ringing artifacts in image reconstruction and their mitigation. However, the aspect of phase discontinuities, which are critical in holographic imaging, has not been extensively explored. Our study implement both OMP and IHT algorithms in a simulated digital holographic environment, where phase discontinuities are inherent due to the nature of holographic imaging. We analyze how these algorithms perform in the presence of phase discontinuities. We quantitatively analyze the performance of each algorithm in handling phase discontinuities. Additionally, our study delves into the computational efficiency of both algorithms, considering their practical applicability in real-time holographic imaging systems. The results of our comparative analysis provide insights into the advantages and limitations of OMP and IHT in the context of phase discontinuities. Our findings have significant implications for advancing digital holography, particularly in applications requiring precise phase information, such as medical imaging, microscopy, and non-destructive testing.
In the last years Unmanned Vehicles for different environments (UxVs) have been recognized as relevant game changers and key technologies for a wide range of military and civilian applications. Even parallel deploymen...
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We investigate hybrid imaging systems consisting of a lens and a fast post-processing algorithm, where the lens is designed or co-designed with professional systems optical design software. Two approaches have been in...
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ISBN:
(纸本)9781510645868
We investigate hybrid imaging systems consisting of a lens and a fast post-processing algorithm, where the lens is designed or co-designed with professional systems optical design software. Two approaches have been investigated: adapt the optimization criterion to the use of a unique deconvolution filter by requiring uniformity of the modulation transfer functions (MTF) over the field of view, or use piecewise-constant deconvolution to adapt the processing algorithm to spatial variations of the MTF in conventionally designed optical systems. By studying the evolution of the deconvolution performance across the field of view in systems optimized with these two approaches, we highlight that the optimal use of post-processing algorithm leads to lenses whose intrinsic performance varies little in the field of view, with however a significant amount of appropriate aperture aberrations but well suited to be post-processed.
We describe the challenges and capabilities of implementing a fast, efficient georegistration system on low-power GPU-enabled embedded systems. The input to this are high-resolution aerial images and refined camera me...
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ISBN:
(数字)9781510618022
ISBN:
(纸本)9781510618022
We describe the challenges and capabilities of implementing a fast, efficient georegistration system on low-power GPU-enabled embedded systems. The input to this are high-resolution aerial images and refined camera metadata, the output are registered aerial images that can be used e.g. in moving object detection and tracking algorithms. The transformations required in the geoprojections in this implementation are obtained from our recent fast Structure-from-Motion (SfM) and georegistration method-BA4S. A real-time warping of the highresolution 3-channel imaged is implemented on GPU in this work which allows a fast geoprojection on a low-power embedded system. Our benchmarks show the effectiveness of the implementation and compared its performance on different hardware platforms. We propose future application in real-time on-device processing, given initial speeds on embedded systems.
Despite the benefits introduced by robotic systems in abdominal Minimally Invasive Surgery (MIS), major complications can still affect the outcome of the procedure, such as intra-operative bleeding. One of the causes ...
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Despite the benefits introduced by robotic systems in abdominal Minimally Invasive Surgery (MIS), major complications can still affect the outcome of the procedure, such as intra-operative bleeding. One of the causes is attributed to accidental damages to arteries or veins by the surgical tools, and some of the possible risk factors are related to the lack of sub-surface visibilty. Assistive tools guiding the surgical gestures to prevent these kind of injuries would represent a relevant step towards safer clinical procedures. However, it is still challenging to develop computer vision systems able to fulfill the main requirements: (i) long term robustness, (ii) adaptation to environment/object variation and (iii) real time processing. The purpose of this paper is to develop computer vision algorithms to robustly track soft tissue areas (Safety Area, SA), defined intra-operatively by the surgeon based on the real-time endoscopic images, or registered from a pre-operative surgical plan. We propose a framework to combine an optical flow algorithm with a tracking-by-detection approach in order to be robust against failures caused by: (i) partial occlusion, (ii) total occlusion, (iii) SA out of the field of view, (iv) deformation, (v) illumination changes, (vi) abrupt camera motion, (vii), blur and (viii) smoke. A Bayesian inference-based approach is used to detect the failure of the tracker, based on online context information. A Model Update Strategy (MUpS) is also proposed to improve the SA re-detection after failures, taking into account the changes of appearance of the SA model due to contact with instruments or image noise. The performance of the algorithm was assessed on two datasets, representing ex-vivo organs and in-vivo surgical scenarios. Results show that the proposed framework, enhanced with MUpS, is capable of maintain high tracking performance for extended periods of time (similar or equal to 4 min - containing the aforementioned events) with high precisi
The proceedings contain 31 papers. The topics discussed include: latent common origin of bilateral filter and non-local means filter;a new edge detection algorithm in imageprocessing based on LIP-ratio approach;edge-...
ISBN:
(纸本)9780819479259
The proceedings contain 31 papers. The topics discussed include: latent common origin of bilateral filter and non-local means filter;a new edge detection algorithm in imageprocessing based on LIP-ratio approach;edge-detected detail enhancement through synthesis of multi-light images;a method for blind estimation of spatially correlated noise characteristics;a robust and fast approach for multiple image components stitching;color-to-grayscale conversion with color clustering and significance criteria;key points selection by using zernike polynomials;efficient implementation of kurtosis based no reference image sharpness metric;exploiting DCT masking effect to improve the perceptual quality of data hiding;hierarchical representation of objects using shock graph methods;hand-movement-based in-vehicle driver/front-seat passenger discrimination for centre console controls;and novel medical image enhancement algorithms.
We propose a sparsity-based denoising algorithm for digital holography retrieved wrapped phase maps (WPMs) mod 2 pi by using a modified version of the SPADEDH (SPArsity DEnoising of Digital Holograms) algorithm, propo...
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ISBN:
(纸本)9780819496041
We propose a sparsity-based denoising algorithm for digital holography retrieved wrapped phase maps (WPMs) mod 2 pi by using a modified version of the SPADEDH (SPArsity DEnoising of Digital Holograms) algorithm, proposed in [1]. We test the proposed method on both simulated wrapped phase reconstructions and experimental wrapped phase maps obtained by digital holograms of living cells. Finally, we also show that the proposed algorithm can be used as a helper for the typical local phase unwrapping algorithms.
We have designed and constructed the calibration system of line standards such as tape and rule for the secondary calibration laboratories. The system consists of the main body with linear stage and linear encoder, th...
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ISBN:
(纸本)9780819496041
We have designed and constructed the calibration system of line standards such as tape and rule for the secondary calibration laboratories. The system consists of the main body with linear stage and linear encoder, the optical microscope with digital camera, and the computer. The base of the system is a aluminum profile with 2.9 m length, 0.09 m height and 0.18 m width. The linear stage and the linear encoder are fixed on the aluminum profile. The micro-stage driven by micrometer is fixed on the carriage of the long linear stage, and the optical microscope with digital camera and the tablet PC are on the this stage. The linear encoder counts the moving distance of the linear stage with resolution of 1 mu m and its counting value is transferred to the tablet PC. The image of the scale mark of the tape is captured by the CCD camera of optical microscope and transferred to the PC through USB interface. The computer automatically determines the center of the scale mark by imageprocessing technique and at the same time reads the moving distance of the linear stage. As a result, the computer can calculate the interval between the scale marks of the tape. In order to achieve the high accuracy, the linear encoder should be calibrated using the laser interferometer or the rigid steel rule. This calibration data of the linear encoder is stored at the computer and the computer corrects the reading value of the linear encoder. In order to determine the center of the scale mark, we use three different algorithms. First, the image profile over specified threshold level is fitted in even order polynomial and the axis of the polynomial is used as the center of the line. Second, the left side and right side areas at the center of the image profile are calculated so that two areas are same. Third, the left and right edges of the image profile are determined at every intensity level of the image and the center of the graduation is calculated as an average of the centers of the left a
We demonstrate the improvement of the quality of the image captured by TS4 - the commercially available THz passive camera manufactured by ThruVision systems Ltd. The measurements range of this device reaches 10 meter...
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ISBN:
(纸本)9780819492876
We demonstrate the improvement of the quality of the image captured by TS4 - the commercially available THz passive camera manufactured by ThruVision systems Ltd. The measurements range of this device reaches 10 meters. Our approach is based on application of novel spatial filters and algorithms, developed by us for computer processing of passive THz images produced by the various THz cameras. In our opinion, the most important result of this paper consists in a demonstration of the possibility of using a passive THz camera to observe a difference in temperature on the human skin if this difference is caused by different temperatures in the inside of the body. Such possibility was proposed by Vyacheslav Trofimov on the Conference in Baltimore (April 2012) as well as and in [20]. We discuss two physical experiments, in which a person drinks hot and cold water. After computer processing of images captured by passive THz camera TS4 we may see the pronounced temperature trace on the human body. We illustrate this phenomenon by a series of images captured by passive THz camera in real time. As we believe, these experiments allow us wide applications of passive THz cameras for the detection of objects concealed in the inside of the human body because the difference in temperature that will be reflected on the human skin. Modern passive THz cameras have not enough resolution in temperature to see this difference. However, computer processing allows us to enhance it for this application. Using computer processing one may enhance the image quality and delete noise on the images. In some cases, it is possible to achieve full de-noising of the image.
Currently, both the market and the academic communities have required applications based on image and video processing with several real-time constraints. On the other hand, detection of moving objects is a very impor...
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Currently, both the market and the academic communities have required applications based on image and video processing with several real-time constraints. On the other hand, detection of moving objects is a very important task in mobile robotics and surveillance applications. In order to achieve an alternative design that allows for rapid development of real time motion detection systems, this paper proposes a hardware architecture for motion detection based on the background subtraction algorithm, which is implemented on FPGAs (Field Programmable Gate Arrays). For achieving this, the following steps are executed: (a) a background image (in gray-level format) is stored in an external SRAM memory, (b) a low-pass filter is applied to both the stored and current images, (c) a subtraction operation between both images is obtained, and (d) a morphological filter is applied over the resulting image. Afterward, the gravity center of the object is calculated and sent to a PC (via RS-232 interface). Both the practical results of the motion detection system and synthesis results have demonstrated the feasibility of FPGAs for implementing the proposed algorithms on an FPGA based hardware platform. The implemented system provides one processed pixel per FPGA's clock cycle (after the latency time) and speed-ups the software implementation (using the real-time xPC Target OS from MathWorks) by a factor of 32.
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