2D/3D single-pixel NIR image reconstruction method for outdoor applications in presence of rain

2021 ◽  
Author(s):  
Carlos Osorio Quero ◽  
Daniel Durini Romero ◽  
Jose de Jesus Rangel-Magdaleno ◽  
Jose Martinez-Carranza ◽  
Ruben Ramos-Garcia
2020 ◽  
Vol 29 (1) ◽  
pp. 220-230
Author(s):  
Marek Siarkowski ◽  
Tomasz Mrozek ◽  
Janusz Sylwester ◽  
Michalina Litwicka ◽  
Magdalena Dąbek

AbstractIn this work we aimed to develop the image reconstruction algorithm without any analytical simplifications and restrictions. In our method we abandon Fourier’s approach to image reconstruction, and instead use the number of counts recorded in each detector pixel, and then reconstruct each image using a classical Richardson-Lucy algorithm. Among similar works performed in the past, our approach is based, for the first time, on the real geometry of STIX. We made a preliminary analysis of expected differences in STIX imaging which may occur due to usage of slightly different geometries. The other difference is that we use single-pixel-response maps. Namely, knowing the instrument geometry we are able to calculate the detector response for point sources covering entire the solar disc. Next, we iteratively combine them with varying weights until the best match between reconstructed and observed detector responses is achieved. Preliminary tests revealed that the developed algorithm reproduces high quality images. The algorithm is moderately fast, but the result comparable to CLEAN algorithm is obtained within 20-50 iteration steps which takes less than 2 seconds on typical portable computer configuration. The location, size and intensity of reconstructed sources are very close to simulated ones. Therefore the algorithm is very well suited for the detailed photometry of the solar HXR sources. Moreover, its simplicity allows to improve photon transmission calculation in case of any grids uncertainties measured after the launch.


Author(s):  
Jingwen Wang ◽  
Xu Wang ◽  
Dan Yang ◽  
Kaiyang Wang

Background: Image reconstruction of magnetic induction tomography (MIT) is a typical ill-posed inverse problem, which means that the measurements are always far from enough. Thus, MIT image reconstruction results using conventional algorithms such as linear back projection and Landweber often suffer from limitations such as low resolution and blurred edges. Methods: In this paper, based on the recent finite rate of innovation (FRI) framework, a novel image reconstruction method with MIT system is presented. Results: This is achieved through modeling and sampling the MIT signals in FRI framework, resulting in a few new measurements, namely, fourier coefficients. Because each new measurement contains all the pixel position and conductivity information of the dense phase medium, the illposed inverse problem can be improved, by rebuilding the MIT measurement equation with the measurement voltage and the new measurements. Finally, a sparsity-based signal reconstruction algorithm is presented to reconstruct the original MIT image signal, by solving this new measurement equation. Conclusion: Experiments show that the proposed method has better indicators such as image error and correlation coefficient. Therefore, it is a kind of MIT image reconstruction method with high accuracy.


2019 ◽  
Vol 3 (4) ◽  
pp. 400-409 ◽  
Author(s):  
Daniel Deidda ◽  
N. A. Karakatsanis ◽  
Philip M. Robson ◽  
Nikos Efthimiou ◽  
Zahi A. Fayad ◽  
...  

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