## Computational Models of Perceptual Organization (2003)

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Venue: | Robotics Institute, Carnegie Mellon University |

Citations: | 4 - 0 self |

### BibTeX

@TECHREPORT{Yu03computationalmodels,

author = {Stella Yu},

title = {Computational Models of Perceptual Organization},

institution = {Robotics Institute, Carnegie Mellon University},

year = {2003}

}

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### Abstract

Perceptual organization refers to the process of organizing sensory input into coherent and interpretable perceptual structures. This process is challenging due to the chicken-and-egg nature between the various sub-processes such as image segmentation, figure-ground segregation and object recognition. Low-level processing requires the guidance of high-level knowledge to overcome noise; while high-level processing relies on low-level processes to reduce the computational complexity. Neither process can be sufficient on its own. Consequently, any system that carries out these processes in a sequence is bound to be brittle. An alternative system is one in which all processes interact with each other simultaneously. In this thesis, we develop a set of simple yet realistic interactive processing models for perceptual organization. We model the processing in the framework of spectral graph theory, with a criterion encoding the overall goodness of perceptual organization. We derive fast solutions for near-global optima of the criterion, and demonstrate the efficacy of the models on segmenting a wide range of real images. Through these models, we are able to capture a variety of perceptual phenomena: a unified treatment of various grouping, figure-ground and depth cues to produce popout, region segmentation and depth segregation in one step; and a unified framework for integrating bottom-up and top-down information to produce an object segmentation from spatial and object attention. We achieve these goals by empowering current spectral graph methods with a principled solution for multiclass spectral graph partitioning; expanded repertoire of grouping cues to include similarity, dissimilarity and ordering relationships; a theory for integrating sparse grouping cues; and a model ...

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Citation Context ...1). Such pairwise comparisons, however, often have difficulty in deriving reliable long-range grouping information. 115sAttempts have been made to find MRF solutions by graph partitioning algorithms (=-=Greig et al., 1989-=-; Ferrari et al., 1995; Boykov et al., 1998; Roy and Cox, 1998; Ishikawa and Geiger, 1998). In particular, sufficient and necessary conditions on the properties of energy functions that can be solved ... |

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Citation Context ... motivated by the gap between discriminative and generative approaches, we are aware of other works that put similar 116sconstraints into clustering algorithms such as K-means (Wagstaff et al., 2000; =-=Wagstaff et al., 2001-=-). Two types of constraints, must-link and cannot-link, are considered. An earlier version of our work (Yu and Shi, 2001a) also considered cannot-link constraints, that is, two nodes cannot assume the... |

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Citation Context ...e bipartitioning (Shi and Malik, 2000) or hypercube partitioning (Hendrickson and Leland, 1995). To get K flat partitions, most prior work uses K eigenvectors (Chan et al., 1994; Shi and Malik, 2000; =-=Weiss, 1999; N-=-g 18 £ £ £set al., 2002), others use more eigenvectors than partitions required (Alpert et al., 1995; Malik et al., 2001). Sometimes, the first trivial eigenvector is discarded (Hall, 1970; Shi and... |

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Citation Context ...l in applications such as circuit layout (Chan et al., 1994; Alpert and Kahng, 1995a), load balancing in parallel computation (Hendrickson and Leland, 1995) and image segmentation in computer vision (=-=Malik et al., 2001-=-). However, the conceptual simplicity of such approaches is lost in the last step which involves recovering a discrete solution from the continuous solution. A majority of the theoretical work on spec... |

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Citation Context ...rity, continuity and symmetry, can be first evaluated through a comparison of feature values associated with the elements, then combined into a measure summarizing the overall grouping compatibility (=-=Wu and Leahy, 1993-=-; Shi and Malik, 1997; Puzicha et al., 1998; Gdalyahu et al., 1998; Sharon et al., 2000). While Gestalt laws have always stressed the similarity of elements in grouping, the effect of local feature co... |

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Citation Context ..., 1998; Roy and Cox, 1998; Ishikawa and Geiger, 1998). In particular, sufficient and necessary conditions on the properties of energy functions that can be solved by minimum cuts have been proven in (=-=Kolmogorov and Zabih, 2002-=-b; Ishikawa, 2003). The work here shows that prior knowledge can be used to guide grouping for discriminative criteria such as normalized cuts (Shi and Malik, 1997), and that their global optima in th... |

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Citation Context ... 1938; Kanizsa, 1979; Palmer, 1999). Consequently, earlier attempts at image segmentation focused on simple low-level feature analysis and enhancement, giving rise to approaches such as thresholding (=-=Sahoo et al., 1988-=-) and edge linking (Witkin, 1983; Canny, 1986; Deriche, 1990). In a basic thresholding approach, a histogram of intensities for all the pixels in the image is first collected. Then a threshold is foun... |

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Citation Context ...of such generic priors on boundary and/or region properties is used in various approaches of image segmentation: 2sactive contours (Kass et al., 1988; Cohen, 1991; Ronfard, 1994), boundary detection (=-=Mumford and Shah, 1985-=-; Nitzberg et al., 1993; Geiger and Kumaran, 1996; Williams and Jacobs, 1997), region growing (Hong and Rosenfeld, 1984; Adams and Bischof, 1994), region competition (Zhu and Yuille, 1996), Markov ran... |

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Citation Context ...l grouping. For some particular forms of ε, such as the above mentioned probability criteria using generative models and minimum cuts criteria in discriminative approaches (Ishikawa and Geiger, 1998;=-= Roy and Cox, 1998-=-; Boykov et al., 1999), the constraints in Eqn (5.3) can be trivially incorporated in an algorithm that optimizes the objective. For the former, Markov Chain Monte Carlo is a general solution techniqu... |

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Citation Context ...y input with known patterns. It has inspired a whole range of generative approaches. One of the most successful applications of this “analysis = synthesis” idea on segmenting real images is given =-=in (Tu and Zhu, 2002-=-). However, despite its rigorous theoretical basis, the implementation often involves too many parameters and heuristics. In this thesis, we adopt the interactive processing point of view for the abov... |

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Citation Context .... Our work is also closely linked to the transduction problem, the goal of which is to complete the labeling of a partially labeled dataset (Joachims, 1999; Jaakkola et al., 1999; Nigam et al., 1999; =-=Szummer and Jaakkola, 2001-=-). If the labeled data set is rich enough to characterize both the structures of the data and the classification task, then using the induced classifier on the labeled set and interpolating it to the ... |

202 |
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Citation Context ...ne to false alarms. In contrast, the interactive processing point of view acknowledges the chickenand-egg nature of perceptual organization (Kelly and Grossberg, 2000; Rumelhart and McClelland, 1986; =-=Grenander and Miller, 1994-=-), and overcomes the issue by engaging all perceptual processing simultaneously. The complicating issue that arises is the interactions among the various perceptual modules. Despite agreement on the n... |

195 | Filters, random fields and maximum entropy (FRAME): Towards a unified theory for texture modeling
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Citation Context ...Adelson, 1988; Malik and Perona, 1990). Some other approaches of texture segmentation go beyond the analysis of features obtained from image filters by also modeling the interactions between filters (=-=Zhu et al., 1998-=-). These Markov random field models (Geman and Geman, 1984) capture contextual dependencies and other statistical characteristics of texture features. a: boundary. b: incoherent. c: disconnected. Figu... |

183 |
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Citation Context ...g and Rosenfeld, 1984; Adams and Bischof, 1994), region competition (Zhu and Yuille, 1996), Markov random fields (Geman and Geman, 1984; Blake and Zisserman, 1987), level-set and variational methods (=-=Sethian, 1996-=-), graph cuts (Shi and Malik, 2000), etc. Figure 1.2: Poor imaging conditions and the interactions between foreground and background can confuse a segmentation algorithm based solely on feature simila... |

179 |
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Citation Context ...e, numerically efficient (Anstreicher and Wolkowicz, 2000), and successful in applications such as circuit layout (Chan et al., 1994; Alpert and Kahng, 1995a), load balancing in parallel computation (=-=Hendrickson and Leland, 1995-=-) and image segmentation in computer vision (Malik et al., 2001). However, the conceptual simplicity of such approaches is lost in the last step which involves recovering a discrete solution from the ... |

178 |
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Citation Context ...lated to image segmentation and has been studied from both contour processing and region processing perspectives. Contour-based approaches perform contour completion by using good curve continuation (=-=Grossberg and Mingolla, 1985-=-; Heitger and von der Heydt, 1993; Mumford, 1993; Ullman, 1976; Williams and Jacobs, 1997), whereas region-based approaches perform image partitioning by using surface properties (Nitzberg et al., 199... |

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Citation Context ...y peceptual pheonomena. However, it is overly flexible and lacks a clear formulation of the overall computation. Some theories focus on interpreting the computation carried out in biological systems (=-=Lee and Mumford, 2003-=-) with high-level concepts only. Parallel distributed processing theory (Rumelhart and McClelland, 1986) is again a biologically inspired computational framework for perceptual processing. It has revo... |

169 | Class-specific, top-down segmentation
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Citation Context ...motion (Blake and Isard, 1998), and segmenting anatomical parts in medical images (McInerney and 119sTerzopoulos, 1996). An alternative to deformable templates for object segmentation is proposed in (=-=Borenstein and Ullman, 2002-=-). Instead of a globally constrained template, object knowledge is represented using pairs of image fragments and their figureground labeling from a training set. The problem of segmentation becomes o... |

165 | Markov random fields with efficient approximations
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Citation Context ...ten have difficulty in deriving reliable long-range grouping information. 115sAttempts have been made to find MRF solutions by graph partitioning algorithms (Greig et al., 1989; Ferrari et al., 1995; =-=Boykov et al., 1998-=-; Roy and Cox, 1998; Ishikawa and Geiger, 1998). In particular, sufficient and necessary conditions on the properties of energy functions that can be solved by minimum cuts have been proven in (Kolmog... |

163 |
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Citation Context ..., 2000; Weiss, 1999; Ng 18 £ £ £set al., 2002), others use more eigenvectors than partitions required (Alpert et al., 1995; Malik et al., 2001). Sometimes, the first trivial eigenvector is discarde=-=d (Hall, 1970-=-; Shi and Malik, 1997). Some works use eigenvectors literally as point coordinates (Shi and Malik, 2000; Alpert and Kahng, 1995b), while many normalize these points to have unit lengths to construct i... |

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Citation Context ...hikawa and Geiger, 1998). In particular, sufficient and necessary conditions on the properties of energy functions that can be solved by minimum cuts have been proven in (Kolmogorov and Zabih, 2002b; =-=Ishikawa, 2003-=-). The work here shows that prior knowledge can be used to guide grouping for discriminative criteria such as normalized cuts (Shi and Malik, 1997), and that their global optima in the continuous doma... |

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Citation Context ... our work was initially motivated by the gap between discriminative and generative approaches, we are aware of other works that put similar 116sconstraints into clustering algorithms such as K-means (=-=Wagstaff et al., 2000-=-; Wagstaff et al., 2001). Two types of constraints, must-link and cannot-link, are considered. An earlier version of our work (Yu and Shi, 2001a) also considered cannot-link constraints, that is, two ... |

148 | A factorization approach to grouping
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Citation Context ...ilarity to pop out. With negative ground-ground connections arising from fragmented background, regularization allows a coherent foreground to stand out. The problem of fragmented background has led (=-=Perona and Freeman, 1998-=-) to adopt an unbalanced criterion which emphasizes the coherence within the figure but not the ground. However, an unbalanced criterion tends to favor small local clusters and thus miss global groupi... |

138 | Geometric hashing: An overview
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Citation Context ...has to be incorporated into the segmentation process. Examples of such segmentation schemes include model-based inference methods: Hough transforms (Illingworth and Kittler, 1988), geometric hashing (=-=Wolfson and Rigoutsos, 1997-=-) and deformable templates (McInerney and Terzopoulos, 1996). The distinction between segmentation and recognition becomes vague. Figure 1.3: Clutter and occlusion pose another major challenge in imag... |

134 |
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Citation Context ...tinct K columns of V are locally optimal only if the weight matrix is semi-positive definite. Though a pairwise weight matrix evaluated from a Gaussian function is guaranteed to be positive definite (=-=Berg et al., 1984-=-), which is what we will use in our experiments, in general it may not be semi-positive definite. In other words, the objective function may not be convex. However, the global-optimality holds even wh... |

129 |
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Citation Context ...00). This view of feature discrimination for grouping is supported by evidence in neurophysiology on elaborate feature detectors in visual cortex (van Essen, 1985), in psychophysics on visual search (=-=Treisman, 1985-=-) and in modeling on texture segmentation (Julesz, 1984; Bergen and Adelson, 1988; Malik and Perona, 1990). Some other approaches of texture segmentation go beyond the analysis of features obtained fr... |

126 |
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(Show Context)
Citation Context ...ness need to be employed. Knowledge of such generic priors on boundary and/or region properties is used in various approaches of image segmentation: 2sactive contours (Kass et al., 1988; Cohen, 1991; =-=Ronfard, 1994-=-), boundary detection (Mumford and Shah, 1985; Nitzberg et al., 1993; Geiger and Kumaran, 1996; Williams and Jacobs, 1997), region growing (Hong and Rosenfeld, 1984; Adams and Bischof, 1994), region c... |