Work in Progress
Super-Resolution

Bauer, T., 2012: Super-Resolution: Die Photometrie von Veränderlichen in Kugelhaufen und Galaxien, BAV Regionaltreffen, Bruno H. Bürgel Sternwarte, 5. May 2012, Hartha (Kreis Döbeln)

 
Super-Resolution Imaging: The Use Case of Optical Astronomy

Super-resolution is well known to increase the resolution of images below the pixel barrier. The work outlines the use case of super-resolution in astronomy science. The current state-of-the-art of high-resolution imaging in astronomy is reviewed, which leads to the problem of super-resolved images. Fundamental properties of astronomical images are demonstrated to define requirements. Astronomical images suffer from low illumination and noise. The range of spatial resolution is found from long-exposure image limited due to atmospheric blur, and a scale of perfect sampling adapted to diffraction-limited observations. Astronomical imaging is a trade-off between resolution and signal-to-noise ratio (S/N). The success of super-resolution is interfered by the quality of data, selection of the method, and a proper definition of the image formation and image reduction pipeline. This work provides a precise definition of the ill-posed and ill-described problem of super-resolution imaging in astronomy. A new method of automatic image registration is presented, which is especially designed for astronomical imagery. Based on the exploration of real astronomical images, the new method provides an accuracy in the order of 0.05 of the pixel dimension. Future milestones are found as the selection of an appropriate method of image deconvolution. With astronomical wide-field imaging, certain optical effects introduce varying point spread and image distortion. These will define the requirements for an appropriate solution to image deconvolution and to complete the task of super-resolution in astronomy. 

Complete library entry

Bauer, T., 2011. Super-Resolution Imaging: The Use Case of Optical Astronomy. Proceedings of the IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing, CGVCVIP 2011, p. 49-59, Rome, Italy, 2011, ISBN 978-972-8939-48-9

State: - Published - 

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Efficient Pixel Binning of Photographs

Pixel binning is a well-known method to reduce the storage capacity of digital images. There remains the question, however, whether binned images obtain an increase of signal or signal-to-noise ratio. Experiments with photographs of point light sources and extended light sources are presented to demonstrate (a) the effect of increase of signal and (b) the success of pixel binning. The work presents a method to compute the signal-to-noise ratio for the binning task. On-chip binning is provided by some hardware devices. On-chip binning will introduce a certain complexity to the calibration of the device and to the derivation of errors obtained from photometry. Electronic imaging and photography are based on physical constraints. It is shown, that binning does not violate the physical law of conservation of energy. Binning will provide averaged pixels at lowered dimension and resolution of the image. Binning does not improve the signal-to-noise ratio or the susceptibility of the device.

Complete library entry

Bauer, T., 2011. Efficient Pixel Binning of Photographs. IADIS International Journal on Computer Science and Information Systems, vol. VI, no. 1, p.1-13, P. Isaías and M. Paprzycki (eds.), 2011. ISSN: 1646-3692

State: Published. 

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Efficient Binning of Photographs

Abstract

Pixel binning is a well-known method to reduce the storage capacity of digital images. There remains the question, however, whether binned images obtain an increase of signal or signal-to-noise ratio. Experiments with photographs of point light sources and extended light sources are presented to demonstrate (a) the effect of increase of signal and (b) the success of pixel binning. The work presents a method to compute the signal-to-noise ratio for the binning task. On-chip binning is provided by some hardware devices. On-chip binning will introduce a certain complexity to the calibration of the device and to the derivation of errors obtained from photometry. Electronic imaging and photography are based on physical constraints. It is shown, that binning does not violate the physical law of conservation of energy. Binning will provide averaged pixels at lowered dimension and resolution of the image. Binning does not improve the signal-to-noise ratio or the susceptibility of the device.

Complete library entry
 
Bauer, Thilo. Efficient Binning of Photographs. Proceedings of the IADIS International Conference, Informatics 2010, 26 - 28 July 2010, Freiburg, Germany, p. 19-25. edited by H. Weghorn, J. Roth and P. Isaias. ISBN: 978-972-8939-19-9


Award Winning Paper

This paper was selected for the "Outstanding Paper Award". The conference committee, taking into account the blind review process, considered this paper of the highest standard.


 
State: Published. 

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Calibration of spectra within sub-pixel range
Thilo Bauer
 
Abstract: A new scientific program evaluates the limits of digital image processing within sub-pixel range. Based on the spectroscopic use case the estimation of the accuracy of the Hoher List REVRAVEL radial velocity spectrograph yielded hints for systematic position deviations in the nineties of the last century. With new tools for statistical imaging and analysis the systematic deviations are shown theoretically and from real measurements. These deviations also limit the spatial resolution of a spectrograph. The deviations depend on optical parameters and the parameters of the profiles themselves. The work presents the current state of development.
 
Invited talk
 
Spektroskopie-Tagung of the ASPA-Arbeitsgemeinschaft, 7.-9. May 2010, Bebra, Germany
 
 
Improving the Accuracy of Position Detection of Point Light Sources on Digital Images

Abstract

The determination of accurate positions of stars is an essential task to obtain a reference coordinate system for precise navigation of ships, airplanes, satellites and space crafts. Stellar positions and proper motions will also help to investigate the structure and evolution of matter in the universe. From astronomical observations systematic errors have been reported by different authors using different techniques to detect and measure positions of point-light sources from digital images. An overview of this problem of image processing is given. The relative subpixel deviation will be defined and described. It provides interesting characteristics independent from the method of position retrieval or point spread introduced by any image deterioration. The relative subpixel deviation defines the lower limit of the achievable precision of positions. The function is the error correction term by itself, which yields a new concept of the error correction. A concept of a new simulation software is presented to further investigate the relative subpixel deviation. Features of the core framework are: support of different optical systems, sources of noise, and detectors types, like monochrome or color CCD and CMOS imagers, their pixel geometry, gaps and varying subpixel sensitivity functions. First results from the simulator software as well as results from new astronomical observations are presented as a proof of concept of the proposed approach to improve the current limit of position accuracy in the order of a few 1/100 of a pixel.

Complete library entry  

Bauer, Thilo. Improving the Accuracy of Position Detection of Point Light Sources on Digital Images. Proceedings of the IADIS Multiconference, Computer Graphics, Visualization, Computer Vision and Image Processing, Algarve, Portugal June 20-22, 2009, p. 3-15, edited by Y. Xiao, T. Amon and P. Kommers. ISBN: 978-972-8924-84-3

State: Published.

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Astroinformatics - A Study about Constraints and Requirements for Next Generation Astronomical Image Processing

Abstract:

A concept of a new software architecture for astronomical image processing is presented. Current approaches of astronomical data extraction are explained: photometry, astrometry and high-resolution imaging. The methods seem incommensurate with each other and suffer from systematic errors caused by known issues. Hints are given, where and how to consolidate these algorithms into a more sophisticated approach to improve data retrieval from images. A detailed discussion of user experience and possible expectations is presented. The analysis yielded current astronomical image processing software based on a shell oriented task collection designed and implemented since the 80ies. From a historical perspective, requirements for any next generation software design can be identified as backward compatibility, platform independence, extensibility, a more intuitive user experience, documentation issues, and long-term reliability. A smooth software transition is proposed. Object-oriented and XML driven approaches may help to combine the existing software packages and future extensions within a common user interface. A unified, formal task description language for image processing is proposed to support generality.

Complete library entry:

Bauer, Thilo. Astroinformatics - A Study about Constraints and Requirements for Next Generation Astronomical Image Processing. Proceedings of the IADIS Multiconference on Computer Science and Information Systems, Amsterdam, 22.-27. July 2008, p. 83-90, IADIS Press, ISBN 978-972-8924-63-8

State: Published. 

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The RAW Image File Format Problem - Applications of Digital SLR Cameras in Astronomy and Science

Abstract

This work describes the application of digital single lens reflex (SLR) cameras in astronomy science. A definition of the term raw file format is given. As with formats like FITS or TIFF, the CR2 file format is explained beeing a dis- closed, and well documented raw file format. Results from raw image file decom- position with different software tools, and a comparison of imaging with a digital SLR camera and a professional grade CCD detector are presented. The analysis of noise and image histograms will help to recover problems with raw file format de- composition tools and their adjustment. Without doubt, digital SLR cameras are suited for special scientific applications. Further implications from this work are a detailed analysis of noise characteristics to achieve high quality imaging at very low light levels from raw files taken with digital SLR cameras.

Complete library entry

Bauer, Thilo. The RAW Image File Format Problem - Applications of Digital SLR Cameras in Astronomy and Science. Proceedings of the 4th Annual Meeting on Information Technology & Computer Science at the BA-University of Cooperative Education, H. Weghorn (Ed.), Stuttgart, ISSN 1614-2519, February 2008

State: Published.

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German Presentation

 
Image of the Month

Interstellar Gas in Cygnus