Elena Anisimova - Academia.edu (original) (raw)

Papers by Elena Anisimova

Acta Polytechnica, 2013

The Point Spread Function (PSF) of the astronomical imaging system is usually approximated by a G... more The Point Spread Function (PSF) of the astronomical imaging system is usually approximated by a Gaussian or Moffat function. For simplification, the astronomical imaging system is considered to be time and space invariant. This means that invariable PSF within an exposed image is assumed. If real wide-field imaging systems are considered, this presumption is not fulfilled. In real systems, stronger optical aberrations are expected (especially coma) at greater distances from the center of the captured image. This impacts the efficiency of stellar astrometry and photometry algorithms, so it is necessary to know the PSF variation. In this paper, we perform the first step toward assigning PSF changes: we study the dependence of the Moffat function fitting parameters (FWHM and the atmospheric scattering coefficient β) on the position of a stellar object.

Proceedings of SPIE, Sep 23, 2014

Object detection is one of the most important procedures in astronomical imaging. This paper deal... more Object detection is one of the most important procedures in astronomical imaging. This paper deals with segmentation of astronomical images based on random forrest classifier. We consider astronomical image data acquired using a photometric system with B, V, R and I filters. Each image is acquired in more realizations. All image realizations are corrected using master dark frame and master at field obtained as an average of hundreds of images. Then a profile photometry is applied to find possible position of stars. The classifier is trained by B, V, R and I image vectors. Training samples are defined by user using ellipsoidal regions (20 selections for both classes: object, background). A number of objects and their positions are compared with astronomical object catalogue using Euclidean distance. We can conclude that the performance of the presented technique is fully comparable to other SoA algorithms.

Proceedings of SPIE, Sep 26, 2013

ABSTRACT Most of the classical approaches to the measurement and modeling of electro-optical imag... more ABSTRACT Most of the classical approaches to the measurement and modeling of electro-optical imaging systems rely on the principles of linearity and space invariance (LSI). In our previous research efforts we have focused on measurement and analysis of images obtained from a double station video observation system MAIA (Meteor Automatic Imager and Analyzer). The video acquisition module of this system contains wide-field input lens which contributes to space-variability of the imaging system. For a precise astronomical measurement over the entire field of view, it is very important to comprehend how the characteristics of the imaging system can affect astrometric and photometric outputs. This paper presents an analysis of how the space-variance of the imaging system can affect precision of astrometric and photometric results. This analysis is based on image data acquired in laboratory experiments and astronomical observations with the wide-field system. Methods for efficient calibration of this system to obtain precise astrometric and photometric measurements are also proposed.

Proceedings of SPIE, Sep 23, 2014

Additional monitoring equipment is commonly used in astronomical imaging. This electro-optical sy... more Additional monitoring equipment is commonly used in astronomical imaging. This electro-optical system usually complements the main telescope during acquisition of astronomical phenomena or supports its operation e.g. evaluating the weather conditions. Typically it is a wide-field imaging system, which consists of a digital camera equipped with fish-eye lens. The wide-field imaging system cannot be considered as a space-invariant because of space-variant nature of its input lens. In our previous research efforts we have focused on measurement and analysis of images obtained from the subsidiary all-sky monitor WILLIAM (WIde-field aLL-sky Images Analyzing Monitoring system). Space-variant part of this imaging system consists of input lens with 180 fi angle of view in horizontal and 154 fi in vertical direction. For a precise astronomical measurement over the entire field of view, it is very important to know how the optical aberrations affect characteristics of the imaging system, especially its PSF (Point Spread Function). Two methods were used for characterization of the space-variant PSF, i.e. measurement in the optical laboratory and estimation using acquired images and Zernike polynomials. Analysis of results obtained using these two methods is presented in the paper. Accuracy of astronomical measurements is also discussed while considering the space-variant PSF of the system.

Proceedings of SPIE, Jan 6, 2015

This paper deals with evaluation and processing of astronomical image data, which are obtained by... more This paper deals with evaluation and processing of astronomical image data, which are obtained by a wide-field all-sky image analyzing monitoring system (WILLIAM). The WILLIAM is an additional experimental camera for project MAIA equipped with wide field lens. The system can detect stellar objects as faint as 6th magnitude. Acquired image data are processed by an algorithm for stellar object detection and identification which is based on coordinates transfer function. Cartesian coordinates at the image data are transformed to horizontal coordinate system. This coordinate system allows searching in astronomical catalogues of stellar objects. This paper presents the components of WILLIAM, its measured electro-optical characteristics and some results of identification.

ABSTRACT This paper deals with image denoising based on the wavelet transform realized by Mallat ... more ABSTRACT This paper deals with image denoising based on the wavelet transform realized by Mallat algorithm and À trous algorithm. The effectiveness of global and subband thresholding techniques are studied on multimedia and astronomical images contaminated by Gaussian noise. Experimental results on several testing images are compared with each other from two objective quality aspects (PSNR, RMSE). Astronomical image denoising techniques differ from those used for multimedia images, because astronomical data are processed by computers and are not evaluated by humans. Thus we show especially the difference between quality criteria related with both types of images after denoising. In case of astronomical data, important scientific criteria as stellar magnitude and FWHM (Full Width at Half Maximum) changes are studied in processed images after noise removal.

Acta Polytechnica, 2011

We report on our efforts to formulate algorithms for image signal processing with the spatially a... more We report on our efforts to formulate algorithms for image signal processing with the spatially and time variant Point-Spread Function (PSF) and inhomogeneous noise of real imaging systems. In this paper we focus on application of the wavelet transform for denoising of the astronomical images with complicated conditions. They influence above all accuracy of the measurements and the new source detection ability. Our aim is to test the usefulness of Wavelet transform (as the standard image processing technique) for astronomical purposes.

ABSTRACT Astronomical image data acquisition under low light conditions causes higher noise occur... more ABSTRACT Astronomical image data acquisition under low light conditions causes higher noise occurrence in these data. There are a lot of noise sources including also the thermally generated noise (dark current) inside used astronomical CCD sensor and the Poisson noise of the photon flux. There are specific image quality criteria in astronomy. These criteria are derived from the algorithms for astronomical image processing and are specific in the field of multimedia signal processing. Astrometric and photometric algorithms provide information about stellar objects: their brightness profile (PSF), position and magnitude. They could fail because of lower SNR. This problem can be solved by subtraction a dark frame from a captured image nowadays. However, this method couldn't work properly in systems with shorter shutter speed and nonlinear sensitivity, such as for example the system MAIA (Meteor Automatic Imager and Analyser). Image data from these system could not been processed by conventional algorithms. Denoising of the astronomical images is therefore still a big challenge for astronomers and people who process astronomical data. Therefore usage of other denoising algorithms is proposed in this paper. We describe our experiences with astronomical image data denoising based on Curvelet and Starlet transform. Novel algorithms have been tested on image data from MAIA system. Their influence on important photometric data like stellar magnitude and FWHM (Full Width at Half Maximum) has been studied and compared with conventional denoising methods.

Acta Polytechnica, 2013

The Point Spread Function (PSF) of the astronomical imaging system is usually approximated by a G... more The Point Spread Function (PSF) of the astronomical imaging system is usually approximated by a Gaussian or Moffat function. For simplification, the astronomical imaging system is considered to be time and space invariant. This means that invariable PSF within an exposed image is assumed. If real wide-field imaging systems are considered, this presumption is not fulfilled. In real systems, stronger optical aberrations are expected (especially coma) at greater distances from the center of the captured image. This impacts the efficiency of stellar astrometry and photometry algorithms, so it is necessary to know the PSF variation. In this paper, we perform the first step toward assigning PSF changes: we study the dependence of the Moffat function fitting parameters (FWHM and the atmospheric scattering coefficient ) on the position of a stellar object.

Acta Polytechnica, 2011

Several algorithms are used nowadays for detecting stellar objects in astronomical images, for ex... more Several algorithms are used nowadays for detecting stellar objects in astronomical images, for example in the DAOPHOTprogram package and in SExtractor (Software for source extraction). Our team has become acquainted with the wavelet transform and its good localization properties. After studying the manual for DAOPHOT and SExtractor, and becoming familiar with the trous algorithm used for calculating the wavelet transform, we set ourselves the task to implement an algorithm for star detection on the basis of the wavelet transform. We focused on detecting stellar objects in complex fields, such as globular clusters and galaxies. This paper describes a stellar object detection algorithm with the help ofthe wavelet transform, and presents our results.

Acta Polytechnica, 2011

We report on our efforts to formulate algorithms for image signal processing with the spatially a... more We report on our efforts to formulate algorithms for image signal processing with the spatially and time variant Point-Spread Function (PSF) and inhomogeneous noise of real imaging systems. In this paper we focus on application of the wavelet transform for denoising of the astronomical images with complicated conditions. They influence above all accuracy of the measurements and the new source detection ability. Our aim is to test the usefulness ofWavelet transform (as the standard image processing technique) for astronomical purposes.

This paper deals with image denoising based on the wavelet transform realized by Mallat algorithm... more This paper deals with image denoising based on the wavelet transform realized by Mallat algorithm and À trous algorithm. The effectiveness of global and subband thresholding techniques are studied on multimedia and astronomical images contaminated by Gaussian noise. Experimental results on several testing images are compared with each other from two objective quality aspects (PSNR, RMSE). Astronomical image denoising techniques differ from those used for multimedia images, because astronomical data are processed by computers and are not evaluated by humans. Thus we show especially the difference between quality criteria related with both types of images after denoising. In case of astronomical data, important scientific criteria as stellar magnitude and FWHM (Full Width at Half Maximum) changes are studied in processed images after noise removal.

Applications of Digital Image Processing XXXVII, 2014

Additional monitoring equipment is commonly used in astronomical imaging. This electro-optical sy... more Additional monitoring equipment is commonly used in astronomical imaging. This electro-optical system usually complements the main telescope during acquisition of astronomical phenomena or supports its operation e.g. evaluating the weather conditions. Typically it is a wide-field imaging system, which consists of a digital camera equipped with fish-eye lens. The wide-field imaging system cannot be considered as a space-invariant because of space-variant nature of its input lens. In our previous research efforts we have focused on measurement and analysis of images obtained from the subsidiary all-sky monitor WILLIAM (WIde-field aLL-sky Images Analyzing Monitoring system). Space-variant part of this imaging system consists of input lens with 180 fi angle of view in horizontal and 154 fi in vertical direction. For a precise astronomical measurement over the entire field of view, it is very important to know how the optical aberrations affect characteristics of the imaging system, especially its PSF (Point Spread Function). Two methods were used for characterization of the space-variant PSF, i.e. measurement in the optical laboratory and estimation using acquired images and Zernike polynomials. Analysis of results obtained using these two methods is presented in the paper. Accuracy of astronomical measurements is also discussed while considering the space-variant PSF of the system.

SPIE Proceedings, 2012

ABSTRACT This paper deals with the criteria definition of image quality in astronomy and their co... more ABSTRACT This paper deals with the criteria definition of image quality in astronomy and their comparison with common multimedia approaches. Astronomical images have typical specific properties - high grayscale bit depth, size, high noise occurrence, sensitivity to point spread function deformation and special processing algorithms. They belong to the class of scientific images as well as medical or similar. Their processing and compression is quite different from the classical approach of multimedia image processing. The new compression algorithm based on JPEG2000 is selected as a distortion source in this paper. Selected image quality criteria (multimedia and optimized for astronomical images) are tested on the set of images from the DEIMOS image database with miscellaneous level of the thermally generated CCD noise. The deformation of the point spread function (PSF) is also measured for chosen compression approach.

SPIE Proceedings, 2013

ABSTRACT Most of the classical approaches to the measurement and modeling of electro-optical imag... more ABSTRACT Most of the classical approaches to the measurement and modeling of electro-optical imaging systems rely on the principles of linearity and space invariance (LSI). In our previous research efforts we have focused on measurement and analysis of images obtained from a double station video observation system MAIA (Meteor Automatic Imager and Analyzer). The video acquisition module of this system contains wide-field input lens which contributes to space-variability of the imaging system. For a precise astronomical measurement over the entire field of view, it is very important to comprehend how the characteristics of the imaging system can affect astrometric and photometric outputs. This paper presents an analysis of how the space-variance of the imaging system can affect precision of astrometric and photometric results. This analysis is based on image data acquired in laboratory experiments and astronomical observations with the wide-field system. Methods for efficient calibration of this system to obtain precise astrometric and photometric measurements are also proposed.

SPIE Proceedings, 2014

Object detection is one of the most important procedures in astronomical imaging. This paper deal... more Object detection is one of the most important procedures in astronomical imaging. This paper deals with segmentation of astronomical images based on random forrest classifier. We consider astronomical image data acquired using a photometric system with B, V, R and I filters. Each image is acquired in more realizations. All image realizations are corrected using master dark frame and master at field obtained as an average of hundreds of images. Then a profile photometry is applied to find possible position of stars. The classifier is trained by B, V, R and I image vectors. Training samples are defined by user using ellipsoidal regions (20 selections for both classes: object, background). A number of objects and their positions are compared with astronomical object catalogue using Euclidean distance. We can conclude that the performance of the presented technique is fully comparable to other SoA algorithms.

Photonics, Devices, and Systems VI, 2015

This paper deals with evaluation and processing of astronomical image data, which are obtained by... more This paper deals with evaluation and processing of astronomical image data, which are obtained by a wide-field all-sky image analyzing monitoring system (WILLIAM). The WILLIAM is an additional experimental camera for project MAIA equipped with wide field lens. The system can detect stellar objects as faint as 6th magnitude. Acquired image data are processed by an algorithm for stellar object detection and identification which is based on coordinates transfer function. Cartesian coordinates at the image data are transformed to horizontal coordinate system. This coordinate system allows searching in astronomical catalogues of stellar objects. This paper presents the components of WILLIAM, its measured electro-optical characteristics and some results of identification.

Acta Polytechnica, Jan 6, 2011

Several algorithms are used nowadays for detecting stellar objects in astronomical images, for ex... more Several algorithms are used nowadays for detecting stellar objects in astronomical images, for example in the DAOPHOT program package and in SExtractor (Software for source extraction). Our team has become acquainted with the wavelet transform and its good localization properties. After studying the manual for DAOPHOT and SExtractor, and becoming familiar with theà trous algorithm used for calculating the wavelet transform, we set ourselves the task to implement an algorithm for star detection on the basis of the wavelet transform. We focused on detecting stellar objects in complex fields, such as globular clusters and galaxies. This paper describes a stellar object detection algorithm with the help of the wavelet transform, and presents our results.

SPIE Proceedings, 2011

ABSTRACT This article will present the use of wavelet transforms for image processing system of M... more ABSTRACT This article will present the use of wavelet transforms for image processing system of MAIA (Meteor Automatic Imager and Analyser). The main objective of these algorithms is the object detection with a high proportion of background noise and complicated imaging function. This noise is generated high brightness of the sky, an image intensifier and CCD sensor used. Analyzed images contain a large number of objects, which have dimensions of only a few pixels. In such cases, it is very difficult to use conventional methods of analysis images that are failing. Application of wavelet transform allows the use of specific features of image function and effectively detect objects.

Acta Polytechnica, 2013

The Point Spread Function (PSF) of the astronomical imaging system is usually approximated by a G... more The Point Spread Function (PSF) of the astronomical imaging system is usually approximated by a Gaussian or Moffat function. For simplification, the astronomical imaging system is considered to be time and space invariant. This means that invariable PSF within an exposed image is assumed. If real wide-field imaging systems are considered, this presumption is not fulfilled. In real systems, stronger optical aberrations are expected (especially coma) at greater distances from the center of the captured image. This impacts the efficiency of stellar astrometry and photometry algorithms, so it is necessary to know the PSF variation. In this paper, we perform the first step toward assigning PSF changes: we study the dependence of the Moffat function fitting parameters (FWHM and the atmospheric scattering coefficient β) on the position of a stellar object.

Proceedings of SPIE, Sep 23, 2014

Object detection is one of the most important procedures in astronomical imaging. This paper deal... more Object detection is one of the most important procedures in astronomical imaging. This paper deals with segmentation of astronomical images based on random forrest classifier. We consider astronomical image data acquired using a photometric system with B, V, R and I filters. Each image is acquired in more realizations. All image realizations are corrected using master dark frame and master at field obtained as an average of hundreds of images. Then a profile photometry is applied to find possible position of stars. The classifier is trained by B, V, R and I image vectors. Training samples are defined by user using ellipsoidal regions (20 selections for both classes: object, background). A number of objects and their positions are compared with astronomical object catalogue using Euclidean distance. We can conclude that the performance of the presented technique is fully comparable to other SoA algorithms.

Proceedings of SPIE, Sep 26, 2013

ABSTRACT Most of the classical approaches to the measurement and modeling of electro-optical imag... more ABSTRACT Most of the classical approaches to the measurement and modeling of electro-optical imaging systems rely on the principles of linearity and space invariance (LSI). In our previous research efforts we have focused on measurement and analysis of images obtained from a double station video observation system MAIA (Meteor Automatic Imager and Analyzer). The video acquisition module of this system contains wide-field input lens which contributes to space-variability of the imaging system. For a precise astronomical measurement over the entire field of view, it is very important to comprehend how the characteristics of the imaging system can affect astrometric and photometric outputs. This paper presents an analysis of how the space-variance of the imaging system can affect precision of astrometric and photometric results. This analysis is based on image data acquired in laboratory experiments and astronomical observations with the wide-field system. Methods for efficient calibration of this system to obtain precise astrometric and photometric measurements are also proposed.

Proceedings of SPIE, Sep 23, 2014

Additional monitoring equipment is commonly used in astronomical imaging. This electro-optical sy... more Additional monitoring equipment is commonly used in astronomical imaging. This electro-optical system usually complements the main telescope during acquisition of astronomical phenomena or supports its operation e.g. evaluating the weather conditions. Typically it is a wide-field imaging system, which consists of a digital camera equipped with fish-eye lens. The wide-field imaging system cannot be considered as a space-invariant because of space-variant nature of its input lens. In our previous research efforts we have focused on measurement and analysis of images obtained from the subsidiary all-sky monitor WILLIAM (WIde-field aLL-sky Images Analyzing Monitoring system). Space-variant part of this imaging system consists of input lens with 180 fi angle of view in horizontal and 154 fi in vertical direction. For a precise astronomical measurement over the entire field of view, it is very important to know how the optical aberrations affect characteristics of the imaging system, especially its PSF (Point Spread Function). Two methods were used for characterization of the space-variant PSF, i.e. measurement in the optical laboratory and estimation using acquired images and Zernike polynomials. Analysis of results obtained using these two methods is presented in the paper. Accuracy of astronomical measurements is also discussed while considering the space-variant PSF of the system.

Proceedings of SPIE, Jan 6, 2015

This paper deals with evaluation and processing of astronomical image data, which are obtained by... more This paper deals with evaluation and processing of astronomical image data, which are obtained by a wide-field all-sky image analyzing monitoring system (WILLIAM). The WILLIAM is an additional experimental camera for project MAIA equipped with wide field lens. The system can detect stellar objects as faint as 6th magnitude. Acquired image data are processed by an algorithm for stellar object detection and identification which is based on coordinates transfer function. Cartesian coordinates at the image data are transformed to horizontal coordinate system. This coordinate system allows searching in astronomical catalogues of stellar objects. This paper presents the components of WILLIAM, its measured electro-optical characteristics and some results of identification.

ABSTRACT This paper deals with image denoising based on the wavelet transform realized by Mallat ... more ABSTRACT This paper deals with image denoising based on the wavelet transform realized by Mallat algorithm and À trous algorithm. The effectiveness of global and subband thresholding techniques are studied on multimedia and astronomical images contaminated by Gaussian noise. Experimental results on several testing images are compared with each other from two objective quality aspects (PSNR, RMSE). Astronomical image denoising techniques differ from those used for multimedia images, because astronomical data are processed by computers and are not evaluated by humans. Thus we show especially the difference between quality criteria related with both types of images after denoising. In case of astronomical data, important scientific criteria as stellar magnitude and FWHM (Full Width at Half Maximum) changes are studied in processed images after noise removal.

Acta Polytechnica, 2011

We report on our efforts to formulate algorithms for image signal processing with the spatially a... more We report on our efforts to formulate algorithms for image signal processing with the spatially and time variant Point-Spread Function (PSF) and inhomogeneous noise of real imaging systems. In this paper we focus on application of the wavelet transform for denoising of the astronomical images with complicated conditions. They influence above all accuracy of the measurements and the new source detection ability. Our aim is to test the usefulness of Wavelet transform (as the standard image processing technique) for astronomical purposes.

ABSTRACT Astronomical image data acquisition under low light conditions causes higher noise occur... more ABSTRACT Astronomical image data acquisition under low light conditions causes higher noise occurrence in these data. There are a lot of noise sources including also the thermally generated noise (dark current) inside used astronomical CCD sensor and the Poisson noise of the photon flux. There are specific image quality criteria in astronomy. These criteria are derived from the algorithms for astronomical image processing and are specific in the field of multimedia signal processing. Astrometric and photometric algorithms provide information about stellar objects: their brightness profile (PSF), position and magnitude. They could fail because of lower SNR. This problem can be solved by subtraction a dark frame from a captured image nowadays. However, this method couldn't work properly in systems with shorter shutter speed and nonlinear sensitivity, such as for example the system MAIA (Meteor Automatic Imager and Analyser). Image data from these system could not been processed by conventional algorithms. Denoising of the astronomical images is therefore still a big challenge for astronomers and people who process astronomical data. Therefore usage of other denoising algorithms is proposed in this paper. We describe our experiences with astronomical image data denoising based on Curvelet and Starlet transform. Novel algorithms have been tested on image data from MAIA system. Their influence on important photometric data like stellar magnitude and FWHM (Full Width at Half Maximum) has been studied and compared with conventional denoising methods.

Acta Polytechnica, 2013

The Point Spread Function (PSF) of the astronomical imaging system is usually approximated by a G... more The Point Spread Function (PSF) of the astronomical imaging system is usually approximated by a Gaussian or Moffat function. For simplification, the astronomical imaging system is considered to be time and space invariant. This means that invariable PSF within an exposed image is assumed. If real wide-field imaging systems are considered, this presumption is not fulfilled. In real systems, stronger optical aberrations are expected (especially coma) at greater distances from the center of the captured image. This impacts the efficiency of stellar astrometry and photometry algorithms, so it is necessary to know the PSF variation. In this paper, we perform the first step toward assigning PSF changes: we study the dependence of the Moffat function fitting parameters (FWHM and the atmospheric scattering coefficient ) on the position of a stellar object.

Acta Polytechnica, 2011

Several algorithms are used nowadays for detecting stellar objects in astronomical images, for ex... more Several algorithms are used nowadays for detecting stellar objects in astronomical images, for example in the DAOPHOTprogram package and in SExtractor (Software for source extraction). Our team has become acquainted with the wavelet transform and its good localization properties. After studying the manual for DAOPHOT and SExtractor, and becoming familiar with the trous algorithm used for calculating the wavelet transform, we set ourselves the task to implement an algorithm for star detection on the basis of the wavelet transform. We focused on detecting stellar objects in complex fields, such as globular clusters and galaxies. This paper describes a stellar object detection algorithm with the help ofthe wavelet transform, and presents our results.

Acta Polytechnica, 2011

We report on our efforts to formulate algorithms for image signal processing with the spatially a... more We report on our efforts to formulate algorithms for image signal processing with the spatially and time variant Point-Spread Function (PSF) and inhomogeneous noise of real imaging systems. In this paper we focus on application of the wavelet transform for denoising of the astronomical images with complicated conditions. They influence above all accuracy of the measurements and the new source detection ability. Our aim is to test the usefulness ofWavelet transform (as the standard image processing technique) for astronomical purposes.

This paper deals with image denoising based on the wavelet transform realized by Mallat algorithm... more This paper deals with image denoising based on the wavelet transform realized by Mallat algorithm and À trous algorithm. The effectiveness of global and subband thresholding techniques are studied on multimedia and astronomical images contaminated by Gaussian noise. Experimental results on several testing images are compared with each other from two objective quality aspects (PSNR, RMSE). Astronomical image denoising techniques differ from those used for multimedia images, because astronomical data are processed by computers and are not evaluated by humans. Thus we show especially the difference between quality criteria related with both types of images after denoising. In case of astronomical data, important scientific criteria as stellar magnitude and FWHM (Full Width at Half Maximum) changes are studied in processed images after noise removal.

Applications of Digital Image Processing XXXVII, 2014

Additional monitoring equipment is commonly used in astronomical imaging. This electro-optical sy... more Additional monitoring equipment is commonly used in astronomical imaging. This electro-optical system usually complements the main telescope during acquisition of astronomical phenomena or supports its operation e.g. evaluating the weather conditions. Typically it is a wide-field imaging system, which consists of a digital camera equipped with fish-eye lens. The wide-field imaging system cannot be considered as a space-invariant because of space-variant nature of its input lens. In our previous research efforts we have focused on measurement and analysis of images obtained from the subsidiary all-sky monitor WILLIAM (WIde-field aLL-sky Images Analyzing Monitoring system). Space-variant part of this imaging system consists of input lens with 180 fi angle of view in horizontal and 154 fi in vertical direction. For a precise astronomical measurement over the entire field of view, it is very important to know how the optical aberrations affect characteristics of the imaging system, especially its PSF (Point Spread Function). Two methods were used for characterization of the space-variant PSF, i.e. measurement in the optical laboratory and estimation using acquired images and Zernike polynomials. Analysis of results obtained using these two methods is presented in the paper. Accuracy of astronomical measurements is also discussed while considering the space-variant PSF of the system.

SPIE Proceedings, 2012

ABSTRACT This paper deals with the criteria definition of image quality in astronomy and their co... more ABSTRACT This paper deals with the criteria definition of image quality in astronomy and their comparison with common multimedia approaches. Astronomical images have typical specific properties - high grayscale bit depth, size, high noise occurrence, sensitivity to point spread function deformation and special processing algorithms. They belong to the class of scientific images as well as medical or similar. Their processing and compression is quite different from the classical approach of multimedia image processing. The new compression algorithm based on JPEG2000 is selected as a distortion source in this paper. Selected image quality criteria (multimedia and optimized for astronomical images) are tested on the set of images from the DEIMOS image database with miscellaneous level of the thermally generated CCD noise. The deformation of the point spread function (PSF) is also measured for chosen compression approach.

SPIE Proceedings, 2013

ABSTRACT Most of the classical approaches to the measurement and modeling of electro-optical imag... more ABSTRACT Most of the classical approaches to the measurement and modeling of electro-optical imaging systems rely on the principles of linearity and space invariance (LSI). In our previous research efforts we have focused on measurement and analysis of images obtained from a double station video observation system MAIA (Meteor Automatic Imager and Analyzer). The video acquisition module of this system contains wide-field input lens which contributes to space-variability of the imaging system. For a precise astronomical measurement over the entire field of view, it is very important to comprehend how the characteristics of the imaging system can affect astrometric and photometric outputs. This paper presents an analysis of how the space-variance of the imaging system can affect precision of astrometric and photometric results. This analysis is based on image data acquired in laboratory experiments and astronomical observations with the wide-field system. Methods for efficient calibration of this system to obtain precise astrometric and photometric measurements are also proposed.

SPIE Proceedings, 2014

Object detection is one of the most important procedures in astronomical imaging. This paper deal... more Object detection is one of the most important procedures in astronomical imaging. This paper deals with segmentation of astronomical images based on random forrest classifier. We consider astronomical image data acquired using a photometric system with B, V, R and I filters. Each image is acquired in more realizations. All image realizations are corrected using master dark frame and master at field obtained as an average of hundreds of images. Then a profile photometry is applied to find possible position of stars. The classifier is trained by B, V, R and I image vectors. Training samples are defined by user using ellipsoidal regions (20 selections for both classes: object, background). A number of objects and their positions are compared with astronomical object catalogue using Euclidean distance. We can conclude that the performance of the presented technique is fully comparable to other SoA algorithms.

Photonics, Devices, and Systems VI, 2015

This paper deals with evaluation and processing of astronomical image data, which are obtained by... more This paper deals with evaluation and processing of astronomical image data, which are obtained by a wide-field all-sky image analyzing monitoring system (WILLIAM). The WILLIAM is an additional experimental camera for project MAIA equipped with wide field lens. The system can detect stellar objects as faint as 6th magnitude. Acquired image data are processed by an algorithm for stellar object detection and identification which is based on coordinates transfer function. Cartesian coordinates at the image data are transformed to horizontal coordinate system. This coordinate system allows searching in astronomical catalogues of stellar objects. This paper presents the components of WILLIAM, its measured electro-optical characteristics and some results of identification.

Acta Polytechnica, Jan 6, 2011

Several algorithms are used nowadays for detecting stellar objects in astronomical images, for ex... more Several algorithms are used nowadays for detecting stellar objects in astronomical images, for example in the DAOPHOT program package and in SExtractor (Software for source extraction). Our team has become acquainted with the wavelet transform and its good localization properties. After studying the manual for DAOPHOT and SExtractor, and becoming familiar with theà trous algorithm used for calculating the wavelet transform, we set ourselves the task to implement an algorithm for star detection on the basis of the wavelet transform. We focused on detecting stellar objects in complex fields, such as globular clusters and galaxies. This paper describes a stellar object detection algorithm with the help of the wavelet transform, and presents our results.

SPIE Proceedings, 2011

ABSTRACT This article will present the use of wavelet transforms for image processing system of M... more ABSTRACT This article will present the use of wavelet transforms for image processing system of MAIA (Meteor Automatic Imager and Analyser). The main objective of these algorithms is the object detection with a high proportion of background noise and complicated imaging function. This noise is generated high brightness of the sky, an image intensifier and CCD sensor used. Analyzed images contain a large number of objects, which have dimensions of only a few pixels. In such cases, it is very difficult to use conventional methods of analysis images that are failing. Application of wavelet transform allows the use of specific features of image function and effectively detect objects.