On the efficiency of techniques for the reduction of impulsive noise in astronomical images

Kurek, A. R.; Błachowicz, Tomasz; Orlov, V. G.; Smołka, Bogdan

doi:10.1093/mnras/stw1983

Cited by 20 publications

(10 citation statements)

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“…One possibility is a reduction of the impulsive noise in difference images. There are many techniques that address the problem (see, e.g., Popowicz et al 2016) and we will search for one that will be optimal for BRITE data. Other planned changes to the photometric pipeline are discussed below.…”

Section: Discussionmentioning

confidence: 99%

BRITE Constellation: data processing and photometry

Popowicz

Pigulski

Bernacki

et al. 2017

A&A

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Context. The BRITE mission is a pioneering space project aimed at the long-term photometric monitoring of the brightest stars in the sky by means of a constellation of nano-satellites. Its main advantage is high photometric accuracy and time coverage inaccessible from the ground. Its main drawback is the lack of cooling of the CCD and the absence of good shielding that would protect sensors from energetic particles. Aims. The main aim of this paper is the presentation of procedures used to obtain high-precision photometry from a series of images acquired by the BRITE satellites in two modes of observing, stare and chopping. The other aim is comparison of the photometry obtained with two different pipelines and comparison of the real scatter with expectations. Methods. We developed two pipelines corresponding to the two modes of observing. They are based on aperture photometry with a constant aperture, circular for stare mode of observing and thresholded for chopping mode. The impulsive noise is a serious problem for observations made in the stare mode of observing and therefore in the pipeline developed for observations made in this mode, hot pixels are replaced using the information from shifted images in a series obtained during a single orbit of a satellite. In the other pipeline, the hot pixel replacement is not required because the photometry is made in difference images. Results. The assessment of the performance of both pipelines is presented. It is based on two comparisons, which use data from six runs of the UniBRITE satellite: (i) comparison of photometry obtained by both pipelines on the same data, which were partly affected by charge transfer inefficiency (CTI), (ii) comparison of real scatter with theoretical expectations. It is shown that for CTI-affected observations, the chopping pipeline provides much better photometry than the other pipeline. For other observations, the results are comparable only for data obtained shortly after switching to chopping mode. Starting from about 2.5 years in orbit, the chopping mode of observing provides significantly better photometry for UniBRITE data than the stare mode.Conclusions. This paper shows that high-precision space photometry with low-cost nano-satellites is achievable. The proposed methods, used to obtain photometry from images affected by high impulsive noise, can be applied to data from other space missions or even to data acquired from ground-based observations.

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Section: Discussionmentioning

confidence: 99%

BRITE Constellation: data processing and photometry

Popowicz

Pigulski

Bernacki

et al. 2017

A&A

Self Cite

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“…However, in practical astronomical observation, the captured images are usually contaminated by different kinds of noises. Since there is no single algorithm that can deal with all noise scenarios, more suitable filters should be adopted or designed to reduce noise 23 . The noise of all the images used for SR reconstruction may have the same probability distribution function, but that of each pixel in one image is somewhat random.…”

Section: Discussionmentioning

confidence: 99%

Super-resolution imaging via aperture modulation and intensity extrapolation

Wang

2018

Sci Rep

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High-resolution telescopic imaging is of great importance in astronomy. Compared to the complexity and huge cost of constructing extremely-large telescopes, super-resolution technique which breaks the diffraction limit of the imaging system can enhance the spatial resolution with compact setup and low cost. In this paper, a novel super-resolution telescopic imaging method based on aperture modulation and intensity extrapolation is demonstrated, with both simulated and experimental studies performed. The simulation results show that the method can enhance the resolving power of a diffraction-limited telescopic imaging system by >5 times in noise-free case, and the improvement still reaches ~1.8 times with a signal-to-noise ratio of only ~10. The preliminary experimental results show a resolution enhancement of ~1.36 times for the limitations of the experimental setup. Better performance is possible with the images for reconstruction denoised and registered more precisely. The method is also useful in wide-field microscopy.

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“…In this model, impulse noise will be understood as a faulty pixel, often called "hot", which can take different values, but for a given pixel the value is approximately constant. Such a noise model can be added based on dark frames obtained for various real image sensors [20]. In our case, we did not analyze impulsive noise; this is due to the fact that in the case of modern imaging sensors impulsive noise is relatively small and easy to effectively remove from the raw images, however impulsive noise data obtained from real camera were also included in our data set (The noisy images are available at: https://tiny.pl/t6xtj).…”

Section: Synthetic Noise Modelmentioning

confidence: 99%

Noise Removal in the Developing Process of Digital Negatives

Szczepański

Giemza

2020

Sensors

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Most modern color digital cameras are equipped with a single image sensor with a color filter array (CFA). One of the most important stages of preprocessing is noise reduction. Most research related to this topic ignores the problem associated with the actual color image acquisition process and assumes that we are processing the image in the sRGB space. In the presented paper, the real process of developing raw images obtained from the CFA sensor was analyzed. As part of the work, a diverse database of test images in the form of a digital negative and its reference version was prepared. The main problem posed in the work was the location of the denoising and demosaicing algorithms in the entire raw image processing pipeline. For this purpose, all stages of processing the digital negative are reproduced. The process of noise generation in the image sensors was also simulated, parameterizing it with ISO sensitivity for a specific CMOS sensor. In this work, we tested commonly used algorithms based on the idea of non-local means, such as NLM or BM3D, in combination with various techniques of interpolation of CFA sensor data. Our experiments have shown that the use of noise reduction methods directly on the raw sensor data, improves the final result only in the case of highly disturbed images, which corresponds to the process of image acquisition in difficult lighting conditions.

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On the efficiency of techniques for the reduction of impulsive noise in astronomical images

Cited by 20 publications

References 50 publications

BRITE Constellation: data processing and photometry

BRITE Constellation: data processing and photometry

Super-resolution imaging via aperture modulation and intensity extrapolation

Noise Removal in the Developing Process of Digital Negatives

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