Shape Coding Research Articles

Bandwidth Efficient and Rate-Matched Low-Density Parity-Check Coded Modulation

A new coded modulation scheme is proposed. At the transmitter, the concatenation of a distribution matcher and a systematic binary encoder performs probabilistic signal shaping and channel coding. At the receiver, the output of a bitwise demapper is fed to a binary decoder. No iterative demapping is performed. Rate adaption is achieved by adjusting the input distribution and the transmission power. The scheme is applied to bipolar amplitude-shift keying (ASK) constellations with equidistant signal points and it is directly applicable to two-dimensional quadrature amplitude modulation (QAM). The scheme is implemented by using the DVB-S2 low-density parity-check (LDPC) codes. At a frame error rate of $10^{-3}$ , the new scheme operates within less than 1.1 dB of the AWGN capacity $\frac{1}{2}\log_2(1+{\mathsf{SNR}})$ at any spectral efficiency between 1 and 5 bits/s/Hz by using only 5 modes, i.e., 4-ASK with code rate 2/3, 8-ASK with 3/4, 16-ASK and 32-ASK with 5/6, and 64-ASK with 9/10.

Neural foundations and functional specificity of number representations

Number is a complex category, as with the word “number” we may refer to different entities. First, it is a perceptual property that characterizes any set of individual items, namely its cardinality. The ability to extract the (approximate) cardinality of sets is almost universal in the animal domain and present in humans since birth. In primates, posterior parietal cortex seems to be a crucial site for this ability, even if the degree of selectivity of numerical representations in parietal cortex reported to date appears much lower compared to that of other semantic categories in the ventral stream. Number can also be intended as a mathematical object, which we humans use to count, measure, and order: a (verbal or visual) symbol that stands for the cardinality of a set, the intensity of a continuous quantity or the position of an item on a list. Evidence points to a convergence towards parietal cortex for the semantic coding of numerical symbols and to the bilateral occipitotemporal cortex for the shape coding of Arabic digits and other number symbols.

Highly efficient contour-based predictive shape coding

A new scheme for contour-based predictive shape coding is proposed aiming to acquire high coding efficiency, where the temporal correlations among object contours are effectively exploited. For a given binary shape image, the object contours are firstly extracted and thinned to be perfect single-pixel width followed by chain-based representation. Then a chain-based motion estimation and compensation technique is developed to remove temporal correlations among object contours to reduce the data to be encoded. Finally, by further exploiting the spatial correlations within chain links, a novel method is introduced to efficiently encode the residuals together with the motion displacements. Experiments are conducted and the results show that the proposed scheme is considerably more efficient than the existing techniques.

Neural shape codes for 3D model retrieval

The paradigm of Convolutional Neural Network (CNN) has already shown its potential for many challenging applications of computer vision, such as image classification, object detection and action recognition. In this paper, the task of 3D model retrieval is addressed by exploiting such promising paradigm. However, 3D models are usually represented with a collection of orderless points, lines and surfaces in a three dimensional space, which makes it difficult to involve the operation of convolution, pooling, etc. Yet, we propose a practical and effective way for applying CNN to 3D model retrieval, by training the network with the depth projections of 3D model. This CNN is regarded as a generic feature extractor for depth image. With large amounts of training data, the learned feature, which is called Neural Shape Codes, can handle various deformation changes that exist in shape analysis. The reported experimental results on several 3D shape benchmark datasets show the superior performance of the proposed method.

Shape representations in the primate dorsal visual stream

The primate visual system extracts object shape information for object recognition in the ventral visual stream. Recent research has demonstrated that object shape is also processed in the dorsal visual stream, which is specialized for spatial vision and the planning of actions. A number of studies have investigated the coding of 2D shape in the anterior intraparietal area (AIP), one of the end-stage areas of the dorsal stream which has been implicated in the extraction of affordances for the purpose of grasping. These findings challenge the current understanding of area AIP as a critical stage in the dorsal stream for the extraction of object affordances. The representation of three-dimensional (3D) shape has been studied in two interconnected areas known to be critical for object grasping: area AIP and area F5a in the ventral premotor cortex (PMv), to which AIP projects. In both areas neurons respond selectively to 3D shape defined by binocular disparity, but the latency of the neural selectivity is approximately 10 ms longer in F5a compared to AIP, consistent with its higher position in the hierarchy of cortical areas. Furthermore, F5a neurons were more sensitive to small amplitudes of 3D curvature and could detect subtle differences in 3D structure more reliably than AIP neurons. In both areas, 3D-shape selective neurons were co-localized with neurons showing motor-related activity during object grasping in the dark, indicating a close convergence of visual and motor information on the same clusters of neurons.

Low rank driven robust facial landmark regression

Localizing facial landmarks is an essential prerequisite to facial image analysis. However, due to the large variability in expression, illumination, pose and the existence of occlusions in the real-world face images, how to localize facial landmarks more efficiently is still a challenging problem. In this paper, we present a low-rank driven regression model for robust facial landmark localization. Our approach consists of low-rank face frontalization and sparse shape constrained cascade regression steps, which lies on, (1) in terms of the low rank prior of face image, we recover such a low-rank face from its deformed image and the associated deformation despite significant distortion and corruption. Alignment of the recovered frontal face image is more simple and effective. And (2) in terms of the sparse coding of face shape on the shape dictionary learnt from training data, sparse shape constrained cascade regression model is proposed to simultaneously suppress the ambiguity in local features and outlier caused by occlusion, and sparse residual error deviated from low-rank face texture is also utilized to predict the occlusion area. Extensive results on several wild benchmarks such as COFW, LFPW and Helen demonstrate that the proposed method is robust to facial occlusions, pose variations and exaggerated facial expressions.

Predictive Coding of Shape Affects the Perceived Luminance of the Surrounding Region

Predictive coding theory suggests that target-related responses in lower brain areas are "explained away" (i.e., reduced) by feedback from higher areas. In practice, predictive coding models rely on feedback signals that must be precisely tuned to each potential target; a computationally simpler and biologically more plausible strategy could be to use spatially distributed feedback affecting both the target and its surrounding region. We tested this hypothesis by measuring luminance perception around potential targets. As in (Murray et al., 2002), we used two stimulus groups: 3D shapes and random lines created by breaking the 3D shapes at their intersections and shuffling the resulting lines. These stimuli differentially activate higher areas, resulting in different amounts of predictive feedback. In each trial, one 3D shape and one random-lines stimulus were shown simultaneously on the left and right of fixation (randomly assigned); each stimulus was presented on a gray disk, and subjects were asked to compare the luminance of these disks (report the side of the brightest disk). One disk had a fixed luminance value while the other varied around that level. We created psychometric functions for the choice probability of each disk as a function of its luminance, and compared these functions for the disk behind the 3D shape versus the one behind the random lines. Results (N=11) indicate that predictive feedback affects background luminance perception. The 3D-shapes disks were perceived brighter and the random-lines disks darker by 4.37% on average. To control for any potential attention bias, we repeated this experiment while observers were engaged in a demanding rapid serial visual presentation task. The perceptual luminance gain was still present, even though attention was engaged away from the 3D shapes and random lines. Thus, predictive feedback signals are not restricted to the predicted input, but also affect the spatial region surrounding it. Meeting abstract presented at VSS 2014

Probe staurosporine drug binding site on protein kinase by PFSC

We used a new approach, protein folding shape code(PFSC), to predict the potential staurosporine binding sites in protein kinases. Firstly, all available three dimensioned(3D) structures of protein kinases in protein databank(PDB) were converted into one-dimensional PFSC description, based on which a PFSC-kinome library was constructed. Secondly, a set of protein kinase-staurosporine complexes were analyzed to define the common structural features of the binding sites. Thirdly, the structural features of the staurosporine binding sites were used to virtually screen the PFSC-kinome library to predict multiple protein receptors that have potential binding capacity for staurosporine. Collectively, the development of the similar method for predicting drug binding site demonstrates that virtual screening protein database can provide valuable information on drug discovery and understanding of pharmacological pathways.

Operationally optimal vertex-based shape coding with arbitrary direction edge encoding structures

The intention of shape coding in the MPEG-4 is to improve the coding efficiency as well as to facilitate the object-oriented applications, such as shape-based object recognition and retrieval. These require both efficient shape compression and effective shape description. Although these two issues have been intensively investigated in data compression and pattern recognition fields separately, it remains an open problem when both objectives need to be considered together. To achieve high coding gain, the operational rate-distortion optimal framework can be applied, but the direction restriction of the traditional eight-direction edge encoding structure reduces its compression efficiency and description effectiveness. We present two arbitrary direction edge encoding structures to relax this direction restriction. They consist of a sector number, a short component, and a long component, which represent both the direction and the magnitude information of an encoding edge. Experiments on both shape coding and hand gesture recognition validate that our structures can reduce a large number of encoding vertices and save up to 48.9% bits. Besides, the object contours are effectively described and suitable for the object-oriented applications. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.JEI.23.4.043009)

Analysis of Mangrove Crab (Scylla sp) Catch Caught by Trap in Different Construction as Operated in Oebelo Village Waters, Central Kupang Sub-district, Kupang Regency

This study is conducted in Oebelo waters, Central Kupang Sub-district from October to December, 2013. It aims to find out the fishing power of trap (ID: bubu) in different types toward mangrove crab catch. It uses observation method by experimental fishing for one month. The findings show that the caught crab consists of 6 species, i.e. Scylla serrata, S. transquabarica, S. olivacea, Portunus pelagicus, Charybdis granulata and C. anisodon which six of these species are caught in every trap type. The caught crab species with the highest proportion is Scylla serrata by 60 crabs (58.823%), then followed by the other species. Trap type having the highest abundance rate is conical type code B 2.3, then conical type code B 3.2 and followed by the other types. Trap code B 2.3 and B 3.2 is the trap prototype having the higher fishing power compared to the others. Trap having the highest CPUE value is conical shape type code B 3.2, followed by semicircular shape code C 3.2, cube-shaped type code A 2.2 and the other types.Trap engineering in this observed crab fishing is one of the important information to improve the trap construction design and mangrove crab fishing method by utilizing trap in the future.

Ideal Coulomb Plasma Approximation in Line Shape Models: Problematic Issues

In weakly coupled plasmas, it is common to describe the microfield using a Debye model. We examine here an “artificial” ideal one-component plasma with an infinite Debye length, which has been used for the test of line shape codes. We show that the infinite Debye length assumption can lead to a misinterpretation of numerical simulations results, in particular regarding the convergence of calculations. Our discussion is done within an analytical collision operator model developed for hydrogen line shapes in near-impact regimes. When properly employed, this model can serve as a reference for testing the convergence of simulations.

Transfer of figural face aftereffects suggests mature orientation selectivity in 8-year-olds’ face coding

Adult face perception mechanisms are tuned to upright faces, and this orientation selectivity is central to adult expertise with upright faces. Children are less expert than adults, and it has been argued that their face mechanisms are less orientation selective than those of adults. Here we used face aftereffects to test this hypothesis by examining whether children’s aftereffects show greater transfer across changes in orientation than do adults’ aftereffects. We adapted 7- to 8-year-old children and adults to figural face distortions in both upright and inverted orientations and examined the size of resulting aftereffects in both upright and inverted test faces. If children’s face mechanisms are less orientation selective than those of adults, then children’s aftereffects should transfer more strongly across changes in orientation. We found no evidence to support this prediction. Children’s and adults’ aftereffects were similarly reduced by orientation differences between adapt and test. These results indicate that children, like adults, show a high degree of orientation selectivity in face shape coding and suggest that neural tuning to face orientation may be mature by 8years of age. Our findings are consistent with an emerging view that many of the key attributes of specialized face perception emerge much earlier in development than previously thought.

Development of a method to recognize punch shapes for progressive dies

A generic method for automatic shape recognition on two-dimensional contours, particularly used for recognizing punch shapes for progressive dies, is presented in this article. In this work, shapes of two-dimensional contours are defined by shape templates using a sequence of symbols, lists, and numbers, and their definitions are stored in a specially designed database for the minimum number of shape definitions to be retrieved during shape recognition for optimal computational efficiency. When a contour is input from a computer-aided design system for shape recognition, the computer-aided design data are translated into shape components and input to the shape recognition device. Upon successful recognition of a shape, the shape code will be composed and its dimensional values will be extracted. Standard or special punch purchase code may be created automatically through this method.

Contour inflections are adaptable features

An object's shape is a strong cue for visual recognition. Most models of shape coding emphasize the role of oriented lines and curves for coding an object's shape. Yet inflection points, which occur at the junction of two oppositely signed curves, are ubiquitous features in natural scenes and carry important information about the shape of an object. Using a visual aftereffect in which the perceived shape of a contour is changed following prolonged viewing of a slightly different-shaped contour, we demonstrate a specific aftereffect for a contour inflection. Control conditions show that this aftereffect cannot be explained by adaptation to either the component curves or to the local orientation at the point of inflection. Further, we show that the aftereffect transfers weakly to a compound curve without an inflection, ruling out a general compound curvature detector as an explanation of our findings. We assume however that there are adaptable mechanisms for coding other specific forms of compound curves. Taken together, our findings provide evidence that the human visual system contains specific mechanisms for coding contour inflections, further highlighting their role in shape and object coding.

Hybrid scheme for efficient shape coding

A contour-based scheme for near lossless shape coding is proposed aiming to acquire high coding efficiency. For a given shape image, object contours are firstly extracted and then thinned to be perfect single-pixel width. Next they are transformed into chain-based representation and divided into different chain segments based on link directions. Thirdly, two fundamental coding modes are designed and developed to encode different types of chain segments, where the spatial correlations within object contours are analyzed and exploited to improve the coding efficiency as high as possible. Finally, a fast and efficient mode selection method is introduced to select the one that can produce shorter code length out of the two modes for each chain segment. Experiments are conducted and the results show that the proposed scheme is considerably more efficient than the existing techniques.

The neural representation of faces and bodies in motion and at rest

The neural organization of person processing relies on brain regions functionally selective for faces or bodies, with a subset of these regions preferring moving stimuli. Although the response properties of the individual areas are well established, less is known about the neural response to a whole person in a natural environment. Targeting an area of cortex that spans multiple functionally-selective face and body regions, we examined the relationship among neural activity patterns elicited in response to faces, bodies, and people in static and moving displays. When both stimuli were static or moving, pattern classification analyses indicated highly discriminable responses to faces, bodies, and whole people. Neural discrimination transferred in both directions between representations created from moving or static stimuli. It transferred also to stimuli experienced across static and dynamic presentations (one static and the other dynamic). In both transfer cases, however, discrimination accuracy decreased relative to the case where the representations were both created and tested with static or moving forms. Next, we examined the relative contribution of activity pattern and response magnitude to discrimination by comparing classifiers that operated with magnitude-normalized scans with classifiers that retained pattern and magnitude information. When both stimuli were moving or static, response magnitude contributed to classification, but the spatially distributed activity pattern accounted for most of the discrimination. Across static and moving presentations, activity pattern accounted completely for the discriminability of neural responses to faces, bodies, and people, with no contribution from response magnitude. Combined, the results indicate redundant and flexible access to person-based shape codes from moving and static presentations. The transfer of shape information across presentation types that preferentially access dorsal and ventral visual processing streams indicates that a common shape code may ground functional divisions in the processing of face and body information.

Bag of contour fragments for robust shape classification

Shape representation is a fundamental problem in computer vision. Current approaches to shape representation mainly focus on designing low-level shape descriptors which are robust to rotation, scaling and deformation of shapes. In this paper, we focus on mid-level modeling of shape representation. We develop a new shape representation called Bag of Contour Fragments (BCF) inspired by classical Bag of Words (BoW) model. In BCF, a shape is decomposed into contour fragments each of which is then individually described using a shape descriptor, e.g., the Shape Context descriptor, and encoded into a shape code. Finally, a compact shape representation is built by pooling shape codes in the shape. Shape classification with BCF only requires an efficient linear SVM classifier. In our experiments, we fully study the characteristics of BCF, show that BCF achieves the state-of-the-art performance on several well-known shape benchmarks, and can be applied to real image classification problem.

Screened Poisson Hyperfields for Shape Coding

We present a novel perspective on shape characterization using the screened Poisson equation. We discuss that the effect of the screening parameter is a change of measure of the underlying metric space. Screening also indicates a conditioned random walker biased by the choice of measure. A continuum of shape fields is created by varying the screening parameter or, equivalently, the bias of the random walker. In addition to creating a regional encoding of the diffusion with a different bias, we further break down the influence of boundary interactions by considering a number of independent random walks, each emanating from a certain boundary point, whose superposition yields the screened Poisson field. Probing the screened Poisson equation from these two complementary perspectives leads to a high-dimensional hyperfield: a rich characterization of the shape that encodes global, local, interior, and boundary interactions. To extract particular shape information as needed in a compact way from the hyperfield, we apply various decompositions either to unveil parts of a shape or parts of a boundary or to create consistent mappings. The latter technique involves lower-dimensional embeddings, which we call screened Poisson encoding maps (SPEM). The expressive power of the SPEM is demonstrated via illustrative experiments as well as a quantitative shape retrieval experiment over a public benchmark database on which the SPEM method shows a high-ranking performance among the existing state-of-the-art shape retrieval methods.

Evaluating the effectiveness of therapy based around Shape Coding to develop the use of regular past tense morphemes in two children with language impairments

It has been suggested that difficulties with tense and agreement marking are a core feature of language impairment. Hence, studies are required that analyse the effectiveness of intervention in this area, including consideration of whether changes seen in therapy sessions generalize to spontaneous speech. This study assessed the effectiveness of therapy based around Shape Coding in developing the use of the regular past tense morpheme -ed in two school-aged children with language impairments. It also considered whether participants benefited from additional generalization therapy in order to start using target forms in their spontaneous speech. The former was assessed using a sentence completion task and the latter by a conversational task with blind assessors. One participant improved markedly in sentence completion but did not gain in the conversation task until after the generalization therapy. The other made more modest gains on the sentence completion task and seemed to generalize to the conversation task without recourse to the generalization therapy. Larger studies are required to confirm these interpretations and to determine whether they are applicable to the wider population of children with language impairments.

Safety sign comprehension by students, adult workers and disabled persons with cerebral palsy

This research carried out comprehension testing on a set of symbol-based safety signs using three diverse groups of participants that included adult workers, college students and persons afflicted with cerebral palsy. Few studies have examined “differently abled” populations with respect to safety signs. Open comprehension testing of a set of 17 ISO (International Organization for Standardization) symbol-based safety signs was carried out using ISO 9186 criteria. The intended message for each safety sign was conveyed via two components, a graphical symbol and a surrounding shape–color background. Results showed that most of the signs were not well understood. In some cases, participants were able to correctly understand the meaning of the symbol, but failed to understand the meaning of the shape–color code or vice versa. In general, the adult workers and college students achieved higher comprehension scores than individuals with cerebral palsy. Despite the lower scores obtained by the cerebral palsy group, the pattern of comprehension levels for the “good” and “bad” signs were similar across the three groups. Other findings included statistically significant associations between comprehension and the individual/experience variables (e.g., age, gender, and have a driver’s license). Issues associated with categorizing participant responses, including the use of criteria for separately evaluating the meaning of the symbols and color–shape codes, are discussed.