Omnidirectional image and video, also known as 360 image and 360 video, are gaining in popularity with the recent growth in availability of cameras and displays that can cope with such type of content. As omnidirectional visual content represents a larger set of information about the scene, it typically requires a much larger volume of information. Efficient compression of such content is therefore important. In this paper, we review the state of the art in compression of omnidirectional visual content, and propose a novel approach to encode omnidirectional images in such a way that they are still viewable on legacy JPEG decoders.
Plenoptic content is becoming increasingly popular thanks to the availability of acquisition and display devices. Thanks to image-based rendering techniques, a plenoptic content can be rendered in real time in an interactive manner allowing virtual navigation through the captured scenes. This way of content consumption enables new experiences, and therefore introduces several challenges in terms of plenoptic data processing, transmission and consequently visual quality evaluation. In this paper, we propose a new methodology to subjectively assess the visual quality of plenoptic content. We also introduce a prototype software to perform subjective quality assessment according to the proposed methodology. The proposed methodology is further applied to assess the visual quality of a light field compression algorithm. Results show that this methodology can be successfully used to assess the visual quality of plenoptic content.
KEYWORDS: High dynamic range imaging, Video, Video coding, Computer programming, Visualization, Video compression, RGB color model, Standards development, Error analysis, Multimedia signal processing
This paper reports the details and results of the subjective evaluations conducted at EPFL to evaluate the responses to the Call for Evidence (CfE) for High Dynamic Range (HDR) and Wide Color Gamut (WCG) Video Coding issued by Moving Picture Experts Group (MPEG). The CfE on HDR/WCG Video Coding aims to explore whether the coding efficiency and/or the functionality of the current version of HEVC standard can be signi_cantly improved for HDR and WCG content. In total, nine submissions, five for Category 1 and four for Category 3a, were compared to the HEVC Main 10 Profile based Anchor. More particularly, five HDR video contents, compressed at four bit rates by each proponent responding to the CfE, were used in the subjective evaluations. Further, the side-by-side presentation methodology was used for the subjective experiment to discriminate small differences between the Anchor and proponents. Subjective results shows that the proposals provide evidence that the coding efficiency can be improved in a statistically noticeable way over MPEG CfE Anchors in terms of perceived quality within the investigated content. The paper further benchmarks the selected objective metrics based on their correlations with the subjective ratings. It is shown that PSNR-DE1000, HDRVDP- 2, and PSNR-Lx can reliably detect visible differences between the proposed encoding solutions and current HEVC standard.
KEYWORDS: High dynamic range imaging, Video, Video surveillance, Cameras, Surveillance, Visualization, Imaging systems, High dynamic range image sensors, Video processing, Sensors
The ability of high dynamic range (HDR) to capture details in environments with high contrast has a significant impact on privacy in video surveillance. However, the extent to which HDR imaging affects privacy, when compared to a typical low dynamic range (LDR) imaging, is neither well studied nor well understood. To achieve such an objective, a suitable dataset of images and video sequences is needed. Therefore, we have created a publicly available dataset of HDR video for privacy evaluation PEViD-HDR, which is an HDR extension of an existing Privacy Evaluation Video Dataset (PEViD). PEViD-HDR video dataset can help in the evaluations of privacy protection tools, as well as for showing the importance of HDR imaging in video surveillance applications and its influence on the privacy-intelligibility trade-off. We conducted a preliminary subjective experiment demonstrating the usability of the created dataset for evaluation of privacy issues in video. The results confirm that a tone-mapped HDR video contains more privacy sensitive information and details compared to a typical LDR video.
Current increasing effort of broadcast providers to transmit UHD (Ultra High Definition) content is likely to increase demand for ultra high definition televisions (UHDTVs). To compress UHDTV content, several alternative encoding mechanisms exist. In addition to internationally recognized standards, open access proprietary options, such as VP9 video encoding scheme, have recently appeared and are gaining popularity. One of the main goals of these encoders is to efficiently compress video sequences beyond HDTV resolution for various scenarios, such as broadcasting or internet streaming. In this paper, a broadcast scenario rate-distortion performance analysis and mutual comparison of one of the latest video coding standards H.265/HEVC with recently released proprietary video coding scheme VP9 is presented. Also, currently one of the most popular and widely spread encoder H.264/AVC has been included into the evaluation to serve as a comparison baseline. The comparison is performed by means of subjective evaluations showing actual differences between encoding algorithms in terms of perceived quality. The results indicate a general dominance of HEVC based encoding algorithm in comparison to other alternatives, while VP9 and AVC showing similar performance.
The Quality of Experience (QoE) provided by autostereoscopic 3D displays strongly depends on the user position. For an optimal image quality, the observer should be located at one of the relevant positions, called sweet spots, where artifacts reducing the QoE, such as crosstalk, are minimum. In this paper, we propose and evaluate a complete active crosstalk reduction system running on an HTC EVO 3D smartphone. To determine the crosstalk level at each position, a full display characterization was performed. Based on the user position and crosstalk profile, the system first helps the user to find the sweet spot using visual feedback. If the user moves away from the sweet spot, then the active crosstalk compensation is performed and reverse stereo phenomenon is corrected. The user preference between standard 2D and 3D modes, and the proposed system was evaluated through a subjective quality assessment. Results show that in terms of depth perception, the proposed system clearly outperforms the 3D and 2D modes. In terms of image quality, 2D mode was found to be best, but the proposed system outperforms 3D mode.
Using Focus of Attention (FoA) as a perceptual process in image and video compression belongs to well-known approaches to increase coding efficiency. It has been shown that foveated coding, when compression quality varies across the image according to region of interest, is more efficient than the alternative coding, when all region are compressed in a similar way. However, widespread use of such foveated compression has been prevented due to two main conflicting causes, namely, the complexity and the efficiency of algorithms for FoA detection. One way around these is to use as much information as possible from the scene. Since most video sequences have an associated audio, and moreover, in many cases there is a correlation between the audio and the visual content, audiovisual FoA can improve efficiency of the detection algorithm while remaining of low complexity. This paper discusses a simple yet efficient audiovisual FoA algorithm based on correlation of dynamics between audio and video signal components. Results of audiovisual FoA detection algorithm are subsequently taken into account for foveated coding and compression. This approach is implemented into H.265/HEVC encoder producing a bitstream which is fully compliant to any H.265/HEVC decoder. The influence of audiovisual FoA in the perceived quality of high and ultra-high definition audiovisual sequences is explored and the amount of gain in compression efficiency is analyzed.
KEYWORDS: Video, Databases, Defect detection, Detection and tracking algorithms, Algorithm development, Video processing, Curium, Head, Signal processing, Analog electronics
Archival of audio-visual databases has become an important discipline in multimedia. Various defects are typ-
ically present in such archives. Among those, one can mention recording related defects such as interference
between audio and video signals, optical related artifacts, recording and play out artifacts such as horizontal
lines, and dropouts, as well as those due to digitization such as diagonal lines. An automatic or semi-automatic
detection to identify such defects is useful, especially for large databases. In this paper, we propose two auto-
matic algorithms for detection of horizontal and diagonal lines, as well as dropouts that are among the most
typical artifacts encountered. We then evaluate the performance of these algorithms by making use of ground
truth scores obtained by human subjects.
High Effciency Video Coding (HEVC) is the latest attempt by ISO/MPEG and ITU-T/VCEG to define the next generation compression standard beyond H.264/MPEG-4 Part 10 AVC. One of the major goals of HEVC is to provide effcient compression for resolutions beyond HDTV. However, the subjective evaluations that led to the selection of technologies were bound to HDTV resolution. Moreover, performance evaluation metrics to report effciency results of this standard are mainly based on PSNR, especially for resolutions beyond HDTV. This paper provides subjective evaluation results to assess the performance of the current HEVC codec for resolutions beyond HDTV.
The properties of wide-field astronomical systems along with specific visual data in astronomical images contribute to
complicated evaluation of acquired image data. The main goal of this paper is to present the advanced processing of
the images obtained from wide-field astronomical systems and to introduce the way how to enhance the accuracy of
astronomical measurements on these systems. The paper also deals with the modelling of the space variant high order
optical aberrations which increase towards margins of the field of view and which distort the point spread function of
optical system and negatively affect the image quality.
This paper presents a study of possible utilization of digital single-lens reflex (DSLR) cameras in astronomy.
The DSLRs have a great advantage over the professional equipments in better cost efficiency with comparable
usability for selected purposes. The quality of electro-optical system in the DSLR camera determines the area
where it can be used with acceptable precision. At first a set of important camera parameters for astronomical
utilization is introduced in the paper. Color filter array (CFA) structure, demosaicing algorithm, image sensor
spectral properties, noise and transfer characteristics are the parameters that belong among the very important
ones and these are further analyzed in the paper. Compression of astronomical images using the KLT approach
is also described below. The potential impact of these parameters on position and photometric measurement
is presented based on the analysis and measurements with the wide-angle lens. The prospective utilization of
consumer DSLR camera as a substitute for expensive devices is discussed.
The principal aim of this paper is to present a general view of the special optical systems used for acquiring of the
astronomical image data, which are commonly called WFC or UWFC (Ultra Wide Field Camera), and of their transfer
characteristics. UWFC image data analysis is very difficult. Images obtained from UWFC systems are distorted by many
various optical aberrations. The influence of optical aberrations increases towards margins of the field of view. These
aberrations distort the point spread function of the optical system and rapidly cut the accuracy of measurements. UWFC
systems frequently have so called spatially variant properties. This paper deals with simulation and modeling of the
UWFC optical systems used in astronomy and their transfer characteristics.
The third order optical aberrations models for LSI/LSV (Linear Space Invariant/Variant) systems is described in this
paper. These models are based on Seidel and Zernike approximating polynomials. Optical aberrations effect to the PSF
(Point Sread Function) of optical imaging systems is described as well. Higher quality and precision of image data can be
obtained with deconvolution of the acquired images and system point spread function. The PSF can be modelled as a
space variant function from the estimation of optical system wavefront aberrations.
This paper deals with simulation and modeling of the optical systems used in astronomy and their transfer characteristics. It is especially focused to the WFC (Wide-Field Camera) and UWFC (Ultra Wide-Field Camera) SV (Space Variant) optical systems. The properties of UWFC astronomical systems along with specific visual data in astronomical images contribute to complicated evaluation of acquired image data. There is an experiment for estimate the optical aberration
of optical systems described in this paper. The results of different deconvolution algorithms, which are used with partially variant model of UWFC optical system, are demonstrated in this paper.
KEYWORDS: Image compression, Astronomy, Cameras, Integral transforms, Stars, Spatial resolution, Quantization, Photometry, Telescopes, Signal to noise ratio
A higher and better precision can been achieved while using more recent observation techniques and superior detection
sensors. It has brought a very rapid increase of data amount as a result. The high spatial resolution (up to ten million
pixels) and a high bit level grey scale images (quantization depth up to 16 bits) are used in astronomy and other scientific
applications. A very large volume of image data has been taken during operation of a modern project of automatic (i.e.
robotic) sky observation systems. The coder based on the Karhunen-Loeve transform (KLT) has been chosen for
astronomical image compression in this paper. The astrometry and photometry measurements have confirmed a
possibility of the coder blocks arrangement with production of an accepted error and a sophisticated data stream.
This paper deals with advanced methods for elimination of the thermally generated charge in the astronomical images,
which were acquired by Charged Coupled Device (CCD) sensor. There exist a number of light images acquired by
telescope, which were not corrected by dark frame. The reason is simple the dark frame doesn't exists, because it was
not acquired. This situation may for instance come when sufficient memory space is not available. There will be
discussed the correction method based on the modeling of the light and dark image in the wavelet domain. As the model
for the dark frame image and for the light image the generalized Laplacian was chosen. The models parameters were
estimated using moment method, whereas an extensive measurement on astronomical camera were proposed and done.
This measurement simplifies estimation of the dark frame model parameters. Finally a set of the astronomical testing
images were corrected and then the objective criteria for an image quality evaluation based on the aperture photometry
were applied.
There are many various applications in astronomy which are using the WFC or UWFC (Ultra Wide-Field Camera)
systems. UWFC systems frequently have so called SV (Space Variant) properties. Images obtained in UWFC systems
are distorted by high order optical aberrations and objects on ultra wide-field images are very small. If we define the PSF
(Point Spread Function) of optical system then we can use some suitable methods for restoration of original image. How
to define the point spread function of LSI (Linear Space Invariant) and LSV (Linear Space Variant) systems is one of the
most challenging questions of this paper.
This paper deals with evaluation and processing of astronomical image data, which are obtained by WFC (Wide-Field
Camera) or UWFC (Ultra Wide-Field Camera) systems. Precision of astronomical image data post-processing and
analyzing is very important. Large amount of different kinds of optical aberrations and distortions is included in these
systems. The amplitude of wavefront aberration error increases towards margins of the FOV (Field of View). Relation
between amount of high order optical aberrations and astrometry measurement precision is discussed in this paper. There
are descriptions of the transfer characteristics of astronomical optical systems presented in this paper. Spatially variant
(SV) optical aberrations negatively affect the transfer characteristics of all system and make it spatially variant as well.
SV model of optical system is presented in this paper. Partially invariant model of optical systems allows using Fourier
methods for deconvolution. Some deconvolution results are shown in this paper.
There are data evaluation of the astronomical optical systems and description of their transfer characteristics presented in
this paper. The real data from the BOOTES (Burst Observer and Optical Transient Exploring Monitor)7 experiment and
from double-station video observation of the meteors are analyzed. The BOOTES is a system for monitoring the optical
transient of GRB (Gamma Ray Bursts). The main goal of the double-station video observation of the meteors is
acquiring of meteors video records and their analysis. Precision of image data post-processing and analyzing, which is
very important for these systems, decreases because of a lot of different kinds of optical aberrations and distortions. It
proves itself at most on the frontier of the field of view (FOV). This paper includes the description of astronomical data
analysis methods and their demos for different values of distortion. There is also a relation between high order
aberrations influence and astrometry measurement precision discussed in this paper.
CMOS imagers based on Active Pixel Sensors (APS) are very important among others because of their possible technical
innovations leading to ultra-low power image acquisition or efficient on-chip image preprocessing. Implementation
of the image processing tasks (focal plane preprocessing and subsequent image processing) can be done effectively only
with the consideration of known transfer characteristics of the imager itself. Geometrical Point Spread Function (PSF)
depends on the certain geometric shape of active area in the particular design of CMOS APS. In this paper, the concept
of Modulation Transfer Function (MTF) analysis is generalized to be applicable to the sampled structures of CMOS
APS. Recalling theoretical results, we have analytically derived the detector MTF in the closed form for some special
active area shapes. The paper also deals with the method based on pseudorandom image pattern with uniform power spectral density (PSD). This method allows to evaluate (in contrast to other methods) spatially invariant MTF including
sampling MTF. It is generally known that a signal acquired by image sensor contains different types of noises. The
superposition of these noises produces noise with a Gaussian distribution. The denoising method based on Bayesian
estimator for implementation into the smart imager is presented.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.