scholarly journals Performance Estimation of Intensity Accumulation Display by Computer-Generated Holograms

2021 ◽  
Vol 11 (16) ◽  
pp. 7729
Author(s):  
Jung-Ping Liu ◽  
Yu-Chih Lin ◽  
Shuming Jiao ◽  
Ting-Chung Poon
Keyword(s):  
Random Phase ◽  
Speckle Noise ◽  
Performance Estimation ◽  
Frame Rate ◽  
Reconstructed Image ◽  
Light Modulator ◽  
Simple Method ◽  
Laser Projector ◽  
Computer Generated Holograms

The image generated by binary computer-generated holograms (CGHs) always suffers from serious speckle noise. Thanks to the fast frame rate of the binary spatial light modulator, the speckle can be significantly suppressed by intensity accumulation, i.e., the sequential display of multiple CGHs of the same scene. If enough randomness is added to the CGHs, the speckle noise can be mostly averaged out. Intuitively, the quality of the reconstructed image should be proportional to the number of intensity accumulation. However, there is no simple method to predict the dependence of the average noise and accumulation number, and we can only know the results after finishing the full computation. In this paper, we propose an empirical formula of the average noise based on the speckle phenomenon in a laser projector. Using this model, we have confirmed that the randomness induced by random phase is equivalent to that induced by random down-sampling for the generation of binary CGHs. In addition, if the computational efficiency is a concern, the CGH calculated with iterations is not recommended for intensity accumulation display. Finally, there is an upper-quality limit of the reconstructed image by intensity accumulation. Thus, a strategy for efficient intensity accumulation is suggested.

scholarly journals Compression of computer-generated holograms in image projection

2017 ◽  
Vol 9 (2) ◽  
pp. 60 ◽  
Author(s):  
Paula Adrianna Kochańska ◽  
Michal Makowski
Keyword(s):  
Spatial Light Modulator ◽  
Graphics Processing Unit ◽  
Random Phase ◽  
Speckle Noise ◽  
Processing Unit ◽  
Light Modulator ◽  
Computer Generated Holography ◽  
Image Projection ◽  
Bit Planes ◽  
Graphics Processing

Computer-generated holography is a technique of a lossless and lens-less forming of images. Methods that use local devices to compute such holograms are very power- and time-consuming. In order to make it possible to transfer the calculations to the cloud, it is necessary to elaborate efficient algorithms of a lossless compression. In this paper two methods of compression are presented and supported by both simulation and experimental results. A lossy compression method omitting certain bit-planes of the holographic data is also presented, which allows insignificant loss of information, while achieving a greater compression ratio. Full Text: PDF ReferencesM. Makowski "Simple holographic projection in color.", Opt. Express 20, 25130-25136 (2012). CrossRef M. Makowski, I. Ducin, K. Kakarenko, J. Suszek, A. Kowalczyk, "Performance of the 4k phase-only spatial light modulator in image projection by computer-generated holography, " Phot. Lett. Poland 8, 26-28 (2016). CrossRef A. Kowalczyk, M. Bieda, M. Makowski, I. Ducin, K. Kakarenko, J. Suszek, A. Sobczyk, "Analysis of computational complexity in holographic lens-less projection," Phot. Lett. Poland 6, 84-86 (2014). CrossRef M. Makowski, "Minimized speckle noise in lens-less holographic projection by pixel separation," Opt. Express 21, 29205-29216 (2013). CrossRef H. Niwase, N. Takada, H. Araki, Y. Maeda, M. Fujiwara, H. Nakayama, T. Kakue, T. Shimobaba, T. Ito "Real-time electroholography using a multiple-graphics processing unit cluster system with a single spatial light modulator and the InfiniBand network." Opt. Eng. 55, 093108-093108 (2016). CrossRef T. Shimobaba and T. Ito, "Random phase-free computer-generated hologram", Opt. Express 23(7) 9549-9554 (2015) CrossRef S.R. Kodituwakku, "Comparison of lossless data compression algorithms for text data", Indian Journal of Computer Science and Engineering Vol 1 No 4 416-426 (2010) DirectLink

scholarly journals Occlusion Culling for Wide-Angle Computer-Generated Holograms Using Phase Added Stereogram Technique

Photonics ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 298
Author(s):  
Juan Martinez-Carranza ◽  
Tomasz Kozacki ◽  
Rafał Kukołowicz ◽  
Maksymilian Chlipala ◽  
Moncy Sajeev Idicula
Keyword(s):  
Point Sources ◽  
Wide Angle ◽  
Computer Generated Holograms ◽  
Propagation Methods ◽  
Propagation Technique ◽  
3D Scene ◽  
Occlusion Culling ◽  
Fourier Type ◽  
Cloud Of Points

A computer-generated hologram (CGH) allows synthetizing view of 3D scene of real or virtual objects. Additionally, CGH with wide-angle view offers the possibility of having a 3D experience for large objects. An important feature to consider in the calculation of CGHs is occlusion between surfaces because it provides correct perception of encoded 3D scenes. Although there is a vast family of occlusion culling algorithms, none of these, at the best of our knowledge, consider occlusion when calculating CGHs with wide-angle view. For that reason, in this work we propose an occlusion culling algorithm for wide-angle CGHs that uses the Fourier-type phase added stereogram (PAS). It is shown that segmentation properties of the PAS can be used for setting efficient conditions for occlusion culling of hidden areas. The method is efficient because it enables processing of dense cloud of points. The investigated case has 24 million of point sources. Moreover, quality of the occluded wide-angle CGHs is tested by two propagation methods. The first propagation technique quantifies quality of point reproduction of calculated CGH, while the second method enables the quality assessment of the occlusion culling operation over an object of complex shape. Finally, the applicability of proposed occlusion PAS algorithm is tested by synthetizing wide-angle CGHs that are numerically and optically reconstructed.

scholarly journals Effect of the Use of Metronome Feedback on the Quality of Pediatric Cardiopulmonary Resuscitation

2021 ◽  
Vol 18 (15) ◽  
pp. 8087
Author(s):  
Dongjun Yang ◽  
Wongyu Lee ◽  
Jehyeok Oh
Keyword(s):  
Cardiopulmonary Resuscitation ◽  
Chest Compression ◽  
Healthcare Providers ◽  
Compression Rate ◽  
Audio Feedback ◽  
Simple Method ◽  
Compression Depth ◽  
Pediatric Resuscitation ◽  
Cpr Quality

Although the use of audio feedback with devices such as metronomes during cardiopulmonary resuscitation (CPR) is a simple method for improving CPR quality, its effect on the quality of pediatric CPR has not been adequately evaluated. In this study, 64 healthcare providers performed CPR (with one- and two-handed chest compression (OHCC and THCC, respectively)) on a pediatric resuscitation manikin (Resusci Junior QCPR), with and without audio feedback using a metronome (110 beats/min). CPR was performed on the floor, with a compression-to-ventilation ratio of 30:2. For both OHCC and THCC, the rate of achievement of an adequate compression rate during CPR was significantly higher when performed with metronome feedback than that without metronome feedback (CPR with vs. without feedback: 100.0% (99.0, 100.0) vs. 94.0% (69.0, 99.0), p < 0.001, for OHCC, and 100.0% (98.5, 100.0) vs. 91.0% (34.5, 98.5), p < 0.001, for THCC). However, the rate of achievement of adequate compression depth during the CPR performed was significantly higher without metronome feedback than that with metronome feedback (CPR with vs. without feedback: 95.0% (23.5, 99.5) vs. 98.5% (77.5, 100.0), p = 0.004, for OHCC, and 99.0% (95.5, 100.0) vs. 100.0% (99.0, 100.0), p = 0.003, for THCC). Although metronome feedback during pediatric CPR could increase the rate of achievement of adequate compression rates, it could cause decreased compression depth.

A simple method for evaluating image quality of screen-film system using a high-performance digital camera

2009 ◽  
Author(s):  
Naotoshi Fujita ◽  
Asumi Yamazaki ◽  
Katsuhiro Ichikawa ◽  
Yoshie Kodera
Keyword(s):  
Image Quality ◽  
High Performance ◽  
Digital Camera ◽  
Film System ◽  
Simple Method

Screening Youth Soccer Players by Means of Cognitive Function and Agility Testing

2021 ◽  
pp. 003151252110402
Author(s):  
Nicola Lovecchio ◽  
Gianluca Manes ◽  
Luca Filipas ◽  
Matteo Giuriato ◽  
Antonio La Torre ◽  
...  
Keyword(s):  
Motor Skills ◽  
Smartphone Application ◽  
Inhibitory Response ◽  
Soccer Players ◽  
Early Age ◽  
Unique Combination ◽  
Simple Method ◽  
Gross Motor Skills ◽  
Youth Soccer

Talent identification in sports is a heavily debated topic. Previous studies have separately explored either executive functions or gross motor skills to predict the success of top-level soccer players or, more generally, to characterize elite performance in soccer. However, at mid-childhood, the possibility to scope sport-specific requirements remains elusive. We aimed in this study to investigate a valid and simple method of testing for a unique combination of cognitive and speed abilities for identifying promising soccer players at mid-childhood. We measured cognitive functions by means of a Stroop smartphone application and agility with a T-Drill Ball-success test, in two groups of (a) elite- ( n = 31) and (b) low-division ( n = 37) Italian 7-year-old male soccer players. We administered the tests in a randomized order to both groups. We found better inhibitory control, cognitive flexibility and soccer-specific agility in high-division versus low-division players ( p < .001). Inhibitory response and agility were positively associated with the augmented quality of the performance from low-division players to high-division players ( r = .55; p = .0001). These results suggest that, even at an early age, cognitive control together with soccer-specific skills is associated with better performance.

Effects of Railway Noise on Residents’ in A Residential Area

2021 ◽  
Vol 3 (01) ◽  
pp. 17-28
Author(s):  
Ria Anggreani Syahputri ◽  
Budi Damianto
Keyword(s):  
Noise Level ◽  
Sleep Disturbances ◽  
Sampling Technique ◽  
Residential Area ◽  
Comfort Level ◽  
Simple Method ◽  
Urban Village ◽  
Noise Measurements ◽  
Influence Of Noise

Population growth in Depok City is large and not in accordance with development land causes many residents’ to build houses with conditions <5 meters from the line of Electric Rail Train or Kereta Rel Listrik (KRL); this causes changes in the quality of the environment, including noise. The objective of this study is to determine the noise level, and the results will be compared with the standard noise level of the residential area; also, to find the influence of noise on residents’. This research was conducted in the area of ​​Rawa Geni Raya Street, 1st Neighborhood, Ratu Jaya Urban Village, Depok City. Noise measurements were carried out at 5-points using a simple method with a noise level measuring instrument (SLM). At one time, the measurement was taken for 10 minutes with a reading time of every 5 seconds. The questionnaire was measured using a Purposive Random Sampling technique, and the number of samples was calculated using the Slovin formula. The results of this study indicate that the 5-point noise level exceeds the recommended threshold according to KEPMEN LH 48 of 1996 and PERMENKES 718/1987 at  55 dB(A). The largest value for the 24-hour noise level (LSM) is at point 1, which is 5 m from the KRL line. The noise level on the weekday is 75.32 dB(A) and 74.24 dB(A) on weekends. According to PERMENKES No 718/1987, the location of point 1 should be included in Area D as an industrial zone, plant, railway station, and bus terminal. The results of questionnaires by 34 respondents showed that the noise generated by KRL was noisy and the majority of respondents agreed the noise affected the comfort level; in terms of health, respondents agreed KRL noise caused sleep disturbances and hearing loss.

scholarly journals Deep Learning-Based Wavelet Threshold Function Optimization on Noise Reduction in Ultrasound Images

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zhuxiang Shen ◽  
Wei Li ◽  
Hui Han
Keyword(s):  
Wavelet Transform ◽  
Image Denoising ◽  
Similarity Index ◽  
Speckle Noise ◽  
Disease Diagnosis ◽  
Function Optimization ◽  
Threshold Function ◽  
Ultrasound Images ◽  
Better Than

To explore the utilization of the convolutional neural network (CNN) and wavelet transform in ultrasonic image denoising and the influence of the optimized wavelet threshold function (WTF) algorithm on image denoising, in this exploration, first, the imaging principle of ultrasound images is studied. Due to the limitation of the principle of ultrasound imaging, the inherent speckle noise will seriously affect the quality of ultrasound images. The denoising principle of the WTF based on the wavelet transform is analyzed. Based on the traditional threshold function algorithm, the optimized WTF algorithm is proposed and applied to the simulation experiment of ultrasound images. By comparing quantitatively and qualitatively with the traditional threshold function algorithm, the advantages of the optimized WTF algorithm are analyzed. The results suggest that the image is denoised by the optimized WTF. The mean square error (MSE), peak signal-to-noise ratio (PSNR), and structural similarity index measurement (SSIM) of the images are 20.796 dB, 34.294 dB, and 0.672 dB, respectively. The denoising effect is better than the traditional threshold function. It can denoise the image to the maximum extent without losing the image information. In addition, in this exploration, the optimized function is applied to the actual medical image processing, and the ultrasound images of arteries and kidneys are denoised separately. It is found that the quality of the denoised image is better than that of the original image, and the extraction of effective information is more accurate. In summary, the optimized WTF algorithm can not only remove a lot of noise but also obtain better visual effect. It has important value in assisting doctors in disease diagnosis, so it can be widely applied in clinics.

scholarly journals Encryption Based Image Watermarking Algorithm in 2DWT-DCT Domains

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5540
Author(s):  
Nayeem Hasan ◽  
Md Saiful Islam ◽  
Wenyu Chen ◽  
Muhammad Ashad Kabir ◽  
Saad Al-Ahmadi
Keyword(s):  
Signal To Noise Ratio ◽  
Image Watermarking ◽  
Similarity Index ◽  
Structural Similarity ◽  
Reconstructed Image ◽  
Discrete Wavelet ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Watermarking Scheme

This paper proposes an encryption-based image watermarking scheme using a combination of second-level discrete wavelet transform (2DWT) and discrete cosine transform (DCT) with an auto extraction feature. The 2DWT has been selected based on the analysis of the trade-off between imperceptibility of the watermark and embedding capacity at various levels of decomposition. DCT operation is applied to the selected area to gather the image coefficients into a single vector using a zig-zig operation. We have utilized the same random bit sequence as the watermark and seed for the embedding zone coefficient. The quality of the reconstructed image was measured according to bit correction rate, peak signal-to-noise ratio (PSNR), and similarity index. Experimental results demonstrated that the proposed scheme is highly robust under different types of image-processing attacks. Several image attacks, e.g., JPEG compression, filtering, noise addition, cropping, sharpening, and bit-plane removal, were examined on watermarked images, and the results of our proposed method outstripped existing methods, especially in terms of the bit correction ratio (100%), which is a measure of bit restoration. The results were also highly satisfactory in terms of the quality of the reconstructed image, which demonstrated high imperceptibility in terms of peak signal-to-noise ratio (PSNR ≥ 40 dB) and structural similarity (SSIM ≥ 0.9) under different image attacks.

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