Group Of Frames Research Articles

No Pass Laws Here! Internal Border Controls and the Global 'Hostile Environment'.

This article explores internal border controls in 1980s Britain, examining how they were conceptualised and resisted by a group of activists, the No Pass Laws Here! Group. Drawing on archival research conducted at the Hull History Centre and the Institute of Race Relations and focusing analysis on the Group's public-facing information leaflets and bulletins, this article explores how internal border controls created differentiated access to employment and the welfare state, targeting migrant and racialised residents and citizens. The No Pass Laws Here! Group's framing and analysis, in particular their use of pass laws as a frame through which to apprehend the spread of internal border controls, this article argues, allows us to draw out the continuities between policies developed to maintain colonial rule and those present in the metropole.

Bi-Sequential Video Error Concealment Method Using Adaptive Homography-Based Registration

This paper proposes a novel video error concealment method for the reconstruction of all unknown regions in frames. The proposed method first performs temporal error concealment (TEC) sequentially in forward direction with the propagation of source information for the unknown regions of frames in group-of-frames (GOF). Then, it performs the TEC sequentially in backward direction for the remaining unknown regions in the GOF. For the reconstruction of unknown regions in each target frame in forward and backward TEC stages, we propose an adaptive homography-based registration of the reference frame. The proposed method selects adaptively global or local homography-based registration for the reconstruction of each unknown region. After the backward direction, the TEC is performed in each frame and the spatial error concealment is applied to reconstruct completely the remaining unknown regions with relatively small sizes. The experimental results show that the proposed method gives significantly improved objective and subjective video quality compared with the traditional reconstruction methods. The proposed method also gives comparably good reconstruction results for large size unknown regions and is feasible for practical real-time applications.

Video quality assessment by compact representation of energy in 3D-DCT domain

Video quality assessment (VQA) aims to predict the perceptual quality for improving the performance of practical application systems. However, the traditional methods consider the video as a sequence of two-dimensional images, which conflicts with the fact that a video signal is a three-dimensional volume data. This operation ignores the temporal information and results in a poor consistency with human perception. Hence, the paper presents a novel VQA model by exploring and exploiting the compact representation of energy in the three-dimensional discrete cosine transform (3D-DCT) domain. First, the video is transformed by 3D-DCT for every group of frame (GOF). Then three types of statistical features are derived from the 3D-DCT coefficients to represent energy compaction properties for simulating the process of human visual system (HVS). The parameters of the generalized Gaussian distribution (GGD) are estimated to imitate the marginal distribution of the 3D-DCT coefficients. Three energy ratios are calculated to depict how the video energy distributes over different frequency components. And the mean and variance value of absolute 3D-DCT coefficients are employed to measure the frequency variation of the video. Finally, the differences between the feature of reference video and the feature of distorted video are calculated to predict the quality score of the distorted video. Experimental results show that the proposed VQA method has a good consistency with human perception and is competitive with the state-of-the-art methods.

Video quality assessment using motion-compensated temporal filtering and manifold feature similarity.

Well-performed Video quality assessment (VQA) method should be consistent with human visual systems for better prediction accuracy. In this paper, we propose a VQA method using motion-compensated temporal filtering (MCTF) and manifold feature similarity. To be more specific, a group of frames (GoF) is first decomposed into a temporal high-pass component (HPC) and a temporal low-pass component (LPC) by MCTF. Following this, manifold feature learning (MFL) and phase congruency (PC) are used to predict the quality of temporal LPC and temporal HPC respectively. The quality measures of the LPC and the HPC are then combined as GoF quality. A temporal pooling strategy is subsequently used to integrate GoF qualities into an overall video quality. The proposed VQA method appropriately processes temporal information in video by MCTF and temporal pooling strategy, and simulate human visual perception by MFL. Experiments on publicly available video quality database showed that in comparison with several state-of-the-art VQA methods, the proposed VQA method achieves better consistency with subjective video quality and can predict video quality more accurately.

Nonuniform video size reduction for moving objects.

Moving objects of interest (MOOIs) in surveillance videos are detected and encapsulated by bounding boxes. Since moving objects are defined by temporal activities through the consecutive video frames, it is necessary to examine a group of frames (GoF) to detect the moving objects. To do that, the traces of moving objects in the GoF are quantified by forming a spatiotemporal gradient map (STGM) through the GoF. Each pixel value in the STGM corresponds to the maximum temporal gradient of the spatial gradients at the same pixel location for all frames in the GoF. Therefore, the STGM highlights boundaries of the MOOI in the GoF and the optimal bounding box encapsulating the MOOI can be determined as the local areas with the peak average STGM energy. Once an MOOI and its bounding box are identified, the inside and outside of it can be treated differently for object-aware size reduction. Our optimal encapsulation method for the MOOI in the surveillance videos makes it possible to recognize the moving objects even after the low bitrate video compressions.

Video Stabilization, Camera Motion Pattern Recognition and Motion Tracking Using Spatiotemporal Regularity Flow

In this paper we propose a different approach based on a spatio-temporal feature called the Spatio Temporal Regularity Flow (SPREF) to stabilize unwanted camera motions in a video, recognize the camera motion patterns between consecutive frames and Group of Frames(GOF) and track the motion of an object in a video with the background subtracted. The method for stabilization based on Camera Motion uses the Translational Regularity flow vectors (TSPREF). In this method we fit the TSPREF vectors into parametric model to calculate the unstabilized global motion. An adaptive Gaussian smoothing method is used to smoothen the global motion followed by motion compensation to produce a stabilized sequence. Experimental results are provided and the stabilization achieved is validated using the qualitative measure Interframe Transform Fidelity (ITF).In camera motion pattern recognition we make use of TSPREF vectors to recognize the cognizant camera motion patterns. This is done for consecutive frames as well as Group of Frames(GOF)of different video sequences. In motion tracking we use the TSPREF vectors to track the moving object present in a video. The test videos taken have a still background with one or two moving objects. In all the cases we have the background subtracted from the moving object. 

SPATIAL-TEMPORAL VIDEO QUALITY ASSESSMENT BASED ON TWO-LEVEL TEMPORAL POOLING

In this paper, a video quality assessment method based on two-level temporal pooling is proposed. By dividing a video sequence into groups of frames (GOFs) with variable lengths, a short-term temporal pooling is performed first at the eye fixation level to obtain the GOF quality. The determination of the GOF size is based on empirical observations from subjective tests that evaluate the duration of successive frames based on which steady quality judgment can be made by the human visual system. The video quality is further obtained by a second level of long-term temporal pooling using the GOF quality. The impact of strong impairment in part of the video on the cognitive system is incorporated in the proposed method for video quality assessment. Extensive experimental results have demonstrated the effectiveness of the proposed method for spatial-temporal distortion evaluation considering both regular and irregular frame loss.

Scalable combined H.264/distributed video coding

PurposeThe first purpose of this paper is to propose a scalable video coding scheme providing flexibility in video transmission, especially under wireless environment. The second purpose is to analyze the problem of lengthening the key frame interval in distributed video coding (DVC), and propose an approach to improve the rate‐distortion (RD) performance of DVC for long group‐of‐frames (GOF) size.Design/methodology/approachIn the proposed scheme, a base layer is first obtained from an H.264 coder. When a DVC coder is then used to code the enhancement layer, information in processing the base layer is extracted and analyzed to make multiple side‐information available and reduce error accumulation for DVC coding, thus further improving the performance of the DVC coder.FindingsBy dividing video into base and enhancement layers, the combined video coding architecture enables a flexible video transmission. In addition, several methods are used to improve the RD performance in DVC coding. Simulation shows that the proposed scheme outperforms non‐scalable DVC for long GOF size.Originality/valuePrediction from the decoding loop in base layer encoder largely reduces enhancement layer spatial redundancy. Multiple side‐information provides better estimation for DVC reconstruction. Long prediction loop is more reliable because error accumulation is effectively compensated.

New Temporal Filtering Scheme to Reduce Delay in Wavelet-Based Video Coding

Scalability is an important desirable property of video codecs. Wavelet-based motion-compensated temporal filtering provides the most powerful scheme for scalable video coding and provides high-compression efficiency that competes with the current state of art codecs. However, the delay introduced by the temporal filtering schemes is sometimes very high, which makes them unsuitable for many real-time applications. In this paper, ue propose a new temporal filter set to minimize delay in 3-D wavelet-based video coding. The new filter set gives a performance at par with existing longer filters. The length of the filter can vary from two to any number of frames depending on delay requirements. If the frames are processed as separate groups of frames (GOFs), the proposed filter set will not have any boundary effects at the GOF. Experimental results are presented and conclusions are drawn.

Framing of the 2003 U.S.-Iraq War Demonstrations: An Analysis of News and Partisan Texts

This study examines press coverage of pro- and anti-war demonstrations before and during the 2003 U.S.-led Iraq war. Computer analysis revealed the existence of partisan master frames in texts by pro- and anti-war organizational groups, and that news articles about each group reflected the frames of the group in question more so than the opposing group's frames. An examination of cues of legitimization and delegitimization in the news articles showed that cue words of delegitimization were used more in anti-war articles than in pro-war articles.

Data-folded architecture for running 3-D DWT using 4-tap Daubechies filters

A real-time 3-D sub-band coding (SBC) technique using a discrete wavelet transform is proposed. The main advantages of the proposed scheme lie in the reduction of wait time and diminution of buffer size in 3-D SBC. The major delay which is due to the group of frames (GOF) generation in the temporal direction is decreased by dynamic updating of the transform coefficients. The dynamic updating handles much a lower dimension of data compared to 3-D SBC, and thus facilitates better hardware utilisation with lower overhead. A data-folding architecture is used in unison with the CORDIC-based QMF lattice filters for realisation of 2-D DWTs using a 4-tap Daubechies filter. The data scanning pattern for the spatial domain signal results in a low-complexity control circuit. The multiplierless DWT architecture operating at 100 MHz is implemented on 0.25 μm BiCMOS technology and found to have much lower power dissipation compared to the multiplier-based structures for FIR realisation. The optimised design of the DWT filter using data-folding architecture resulted in an appreciable low memory budget of N2/4+2N for 2-D DWT and O(N2/M) time required for temporal direction decomposition. Hardware utilisation in the proposed architecture is 100%.

Robust color histogram descriptors for video segment retrieval and identification

Effective and efficient representation of color features of multiple video frames or pictures is an important yet challenging task for visual information management systems. Key frame-based methods to represent the color features of a group of frames (GoF) are highly dependent on the selection criterion of the representative frame(s), and may lead to unreliable results. We present various histogram-based color descriptors to reliably capture and represent the color properties of multiple images or a GoF. One family of such descriptors, called alpha-trimmed average histograms, combine individual frame or image histograms using a specific filtering operation to generate robust color histograms that can eliminate the adverse effects of brightness/color variations, occlusion, and edit effects on the color representation. We show the efficacy of the alpha-trimmed average histograms for video segment retrieval applications, and illustrate how they consistently outperform key frame-based methods. Another color histogram descriptor that we introduce, called the intersection histogram, reflects the number of pixels of a given color that is common to all the frames in the GoF. We employ the intersection histogram to develop a fast and efficient algorithm for identification of the video segment to which a query frame belongs. The proposed color histogram descriptors have been included in the ISO standard MPEG-7 after extensive evaluation experiments.

Wavelet-based video coder via bit allocation

We present a video coder based on a bit allocation (BA) scheme for a coding approach where a wavelet-based video compression scheme is used to encode a group of frames (GOF). The proposed new BA method utilizes a Lagrangian multiplier technique to determine the optimal bit rate for each frame of a given GOF in a rate versus weighted distortion sense. The proposed baseline coder sequentially employs the application of the wavelet transform on each frame in the group. In the wavelet domain, an optimal-vector BA (rate-allocation strategy) is being used to distribute the bit budget among the frames. The manipulated frames in each group are quantized and coded using techniques from still-image compression. We describe and demonstrate the performance of the proposed algorithm in wavelet-based coding approaches. The first one, a combination of wavelet still compression and optimal BA (WCBA), is based on frame differences and exploits well the wavelet compression characteristics which keeps, for a given bit budget, the most important features. It does not utilize motion-compensation interpolation or a 3-D wavelet decomposition. In cases where heavy motion is detected, we extend WCBA into a combination of wavelet still compression, optimal BA, motion compensation with block matching, and error correction (WCBAM), which uses block matching for motion estimation, while the residual error of the compression is reduced by applying error correction in the wavelet domain to reduce temporal redundancies.

Frame disputes in environmental controversies: The case of wetland regulations in Louisiana

Stakeholder groups’ arguments for or against regulations represent frames, or versions of reality and visions of solutions. Frame effectiveness, or the ability of a group convincingly to convey its grievances, increases its opportunities to gain valuable resources such as legitimacy, money, facilities, and labor to apply to its agenda for change. This paper uses the constructionist perspective to describe the basic frames advanced by each major group in a contemporary environmental controversy: the role of government in regulating wetland use in Louisiana. Using 91 semis‐tructured interviews as the main data, this paper discusses stakeholder frames from regulatory, regulated, and environmentalist positions and the rhetorical strategies hidden within each group's frames. This paper suggests that the regulated community has greater interpretive dominance in the wetlands controversy than regulators and environmentalists/concerned citizens because the community advances a more diverse set of frames, more effectively “piggybacks” its frames on other central contemporary government criticisms, and is more adept at using “diversionary reframing,” whereby it disregards the costs of wetland loss and shifts the discussion to tangible costs to landowners. Future work on framing in social movements, especially in natural resource disputes, should refine the concept of frame effectiveness and identify recurring strategies that attract public support within disputes.

Proarrhythmic and antiarrhythmic actions of ion channel blockers on arrhythmias in the heart: model study.

We explain why 1) some class I and IV antiarrhythmia drugs could exert proarrhythmic action, 2) some class III drugs are effective in controlling reentrant arrhythmias, and 3) cycle length (CL) oscillation is involved in the termination or initiation of reentry. To explain these phenomena, we employ the following three means: bifurcation analysis, simulation, and model construction. Antiarrhythmia drugs are modeled by varying maximal conductances of Na+, Ca2+, and time-dependent delayed rectifying and time-independent inward rectifying K+ channels in the Beeler-Reuter model, where the model cells are arranged in a ring. Bifurcation analysis predicts that there is a critical ring size (CRS) at which infinite ring behavior suddenly breaks down. Channel blockers can affect CRS in different manners: Na+ and Ca2+ blockers shorten CRS, whereas delayed rectifying K+ channel blockers and the inward K+ channel blockers lengthen CRS. This differential explains why some antiarrhythmia drugs are proarrhythmic (i.e., shorten CRS) whereas others are antiarrhythmic (i.e., lengthen CRS). Simulation is then used to investigate how the drugs affect reentrant rhythms in the neighborhood of the CRS. We find that, in this region, CL, conduction velocity, and action potential duration become oscillatory. As ring size shrinks, the pattern of the oscillation becomes more complex. When the ring shrinks to a certain size, reentry can no longer be sustained, and it terminates after a few oscillatory cycles. To explain the basic mechanism involved in CL oscillation, we then construct a minimal model that contains a low-threshold fast inward current and a high-threshold slow inward current. With this model, we show that the two inward currents, with vastly different activation and inactivation kinetics, cause CL oscillations. Our results thus give theoretical explanations for the experimental finding of Frame's group in canine atrial tricuspid ring in vitro that class IC drugs can bring about stable reentry from nonsustained transient reentry, whereas class III drugs transform stable reentry to complex oscillations in CL. Our results also support the result of Frame's group, in that, in "adjustable" tricuspid rings, CL oscillation becomes more complex and its period becomes shorter as an excitable gap is shortened.