Martin Bernas

Objective and subjective image quality evaluation for security technology

The paper is devoted to the impacts of image compression algorithms on security image data. It compares three fundamentally different evaluation techniques of image objective criteria, subjective criteria and identification. We have selected two typical security image data (a car plate and a face) with different initial quality and we applied three different compression techniques-two professional (JPEG and LuRaWave-LWF) and one implemented (Karhunen-Loeve transform, KLT). A set of compressed images differing in compression rate was derived from each original image data. Finally the MSE as an objective criterion, the subjective image quality according to the ITU-R Rec. 500 and the identification measure were evaluated and compared.

Search for Gamma Ray Burst Quasi Simultaneous Optical Emission with BOOTES-1

The Burst Observer and Optical Transient Exploring System experiment (BOOTES) has been designed to provide an automatic real time observing response to the detection of Gamma Ray Bursts (GRBs). It achieves such response by using wide field cameras attached to small robotic telescopes and imaging in the B, I and R bands. To date we have obtained images for about 50 events with the Wide Field Camera (WFC), starting, in several ocasions, 3 minutes after the burst commenced. One of the last searches resulted in the detection of an optical transient, candidate to be the optical counterpart of the GR.B 000313, although such relation has not been established to absolute certainty yet.

Optical transient monitor

Although there are several optical GRB follow-up systems in operation and/or in development, some of them with a very short response time, they will never be able to provide true simultaneous (no delay) and pre-burst optical data for GRBs. We report on the development and tests of a monitoring experiment expected to be put into test operation in 1998. The system should detect Optical Transients down to mag 6–7 (few seconds duration assumed) over a wide field of view. The system is based on the double CCD wide-field cameras ST8. For the real time evaluation of the signal from both cameras, two TMS 320C40 processors are used. Using two channels differing in spectral sensitivity and processing of temporal sequence of images allows us to eliminate man-made objects and defects of the CCD electronics. The system is controlled by a standard PC computer.

Independent transmission of sign language interpreter in DVB: assessment of image compression

Sign language on television provides information to deaf that they cannot get from the audio content. If we consider the transmission of the sign language interpreter over an independent data stream, the aim is to ensure sufficient intelligibility and subjective image quality of the interpreter with minimum bit rate. The work deals with the ROI-based video compression of Czech sign language interpreter implemented to the x264 open source library. The results of this approach are verified in subjective tests with the deaf. They examine the intelligibility of sign language expressions containing minimal pairs for different levels of compression and various resolution of image with interpreter and evaluate the subjective quality of the final image for a good viewing experience.

Optical observations of GRBs: EN, BART, and OMC

We report on the ongoing projects at the Astronomical Institute Ondrejov. The EN (European Fireball Network) is based on 11 photographic stations and has already provided simultaneous optical data for 100 GRB triggers. A summary and discussion of the obtained results are given as well as discussion of detected candidates. The BART (Burst Alert Robotic Telescope) is a 25 cm aperture remotely controlled system in test operation. The OMC (Optical Monitoring Camera), prepared by a wide international collaboration for the INTEGRAL satellite (launch 2001), will also have capability for the detection of optical transients and optical afterglows of GRBs, assuming that their rate is higher than the GRB rate (caused by different beaming).

Optimized H.264 compression of sign language video

In TV broadcasting deaf people are not able to get information from the audio content. In public television, some programs may be accompanied by a sign language interpreter as a part of the broadcasted signal. As a supplementary service, it would enable more programs to be accessible with a sign language interpreter to assist in comprehension. To be able to transmit such data flow separately, we define the parameters of compression of sign language interpreter image to ensure intelligibility and quality while maintaining low bitrate. This paper deals with specific video compression of Czech sign language interpreter based on regions of interest implemented to the ×264 open source library. The results of this approach are verified in subjective tests with the deaf and hearing evaluators. The experiments examine the intelligibility of sign language expressions containing minimal pairs for different levels of image compression and also evaluate the subjective quality of the final image.

Human vision model for image quality evaluation suitable for smart imager implementation

This article deals with image quality evaluation ofthe compressed images especially for compression format JPEG 2000. It shows evaluation of selected test images (scene with: textures, details, text, color of face, etc.) using selected methods: subjective testing as the reference method, objective testing and two designed human vision models. At the end article compares results of these methods.

Correction of CCD sensor noise

A CCD image sensor introduces noise to an image. This paper deal with main disturbing effects and their corrections. Statistical properties were computed from raw and corrected real CCD images. Some types of noise is possible to reduce by sensor cooling and image processing.

Properties of Karhunen-Loeve Expansion of astronomical images in comparison with other integral transforms

This work deals with the use of Karhunen-Loeve Expansion (KLE) for astronomical image compression. A mathematical algorithm of KLE has been derived using characteristics of (N×N)-dimensional Hilbert space. The KLE frequency domains and their reductions leading to image compression have been studied in comparison with other integral transforms. The following important results have been obtained during accuracy and suitability testing of KLE in astronomical photometry measurements. The achieved results show that KLE is suitable and probably the best method of astronomical image compression.

First results from the Burst Observer and Optical Transient Exploring System station 1 (BOOTES-1)

The Burst Observer and Optical Transient Exploring System (BOOTES) is considered as a part of the preparations for ESA’s INTEGRAL satellite, and is currently being developed in Spain, in collaboration with two Czech institutions. It makes use of two sets of wide-field cameras, 240 km apart, and two robotic 0.3-m telescopes. The first observing station (BOOTES-1) is located in Huelva (Spain) and the first light was obtained in July 1998. During the test phase, it has provided rapid follow-up observations with the wide-field cameras for 19 GRBs detected by BATSE aboard CGRO, and narrow-field imaging for 6 bursts. Limiting magnitudes for any GRB optical afterglow are I∼13 and R∼16.5, a few minutes after the events.