Connectivity-based shape descriptors
- Authors: Sajjanhar, Atul , Lu, Guojun , Zhang, Dengsheng , Zhou, Wanle
- Date: 2010
- Type: Text , Journal article
- Relation: International Journal of Computers and Applications Vol. 32, no. 1 (2010), p. 93-98
- Full Text: false
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- Description: In this paper, we propose a method for indexing and retrieval of images based on shapes of objects. The concept of connectivity is introduced. 3D models are used to represent 2D images. 2D images are decomposed a priori using connectivity which is followed by 3D model construction. 3D model descriptors are obtained for 3D models and used to represent the underlying 2D shapes. We have used spherical harmonics descriptors as the 3D model descriptors. Difference between two images is computed as the Euclidean distance between their descriptors. Experiments are performed to test the effectiveness of spherical harmonics for retrieval of 2D images. The proposed method is compared with methods based on principal components analysis (PCA) and generic Fourier descriptors (GFD). It is found that the proposed method is effective. Item S8 within the MPEG-7 still images content set is used for performing experiments.
Novel spectral descriptor for object shape
- Authors: Sajjanhar, Atul , Lu, Guojun , Zhang, Dengsheng
- Date: 2010
- Type: Text , Book chapter
- Relation: Proceedings of the 11th Pacific Rim Conference on Multimedia: Advances in Multimedia Information Processing p. 58-67
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- Description: In this paper, we propose a novel descriptor for shapes. The proposed descriptor is obtained from 3D spherical harmonics. The inadequacy of 2D spherical harmonics is addressed and the method to obtain 3D spherical harmonics is described. 3D spherical harmonics requires construction of a 3D model which implicitly represents rich features of objects. Spherical harmonics are used to obtain descriptors from the 3D models. The performance of the proposed method is compared against the CSS approach which is the MPEG-7 descriptor for shape contour. MPEG-7 dataset of shape contours, namely, CE-1 is used to perform the experiments. It is shown that the proposed method is effective
Spherical harmonics and distance transform for image representation and retrieval
- Authors: Sajjanhar, Atul , Lu, Guojun , Zhang, Dengsheng , Hou, Jingyu , Chen, Yi-Ping Phoebe
- Date: 2009
- Type: Text , Conference paper
- Relation: Proceedings of the Intelligent Data Engineering and Automated Learning p. 309-316
- Full Text: false
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- Description: In this paper, we have proposed a method for 2D image retrieval based on object shapes. The method relies on transforming the 2D images into 3D space based on distance transform. Spherical harmonics are obtained for the 3D data and used as descriptors for the underlying 2D images. The proposed method is compared against two existing methods which use spherical harmonics for shape based retrieval of images. MPEG-7 Still Images Content Set is used for performing experiments; this dataset consists of 3621 still images. Experimental results show that the performance of the proposed descriptors is significantly better than other methods in the same category.
Corners-based composite descriptor for shapes
- Authors: Sajjanhar, Atul , Lu, Guojun , Zhang, Dengsheng , Zhou, Wanlei
- Date: 2008
- Type: Text , Conference paper
- Relation: Proceedings of the First International Congress on Image and Signal Processing CISP2008 p. 714-718
- Full Text: false
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- Description: In this paper, a composite descriptor for shape retrieval is proposed. The composite descriptor is obtained based upon corner-points and shape region. In an earlier paper, we proposed a composite descriptor based on shape region and shape contour, however, the descriptor was not effective for all perspective and geometric transformations. Hence, we modify the composite descriptor by replacing contour features with corner-points features. The proposed descriptor is obtained from Generic FourierDescriptors (GFD) of the shape region and the GFD ofthe corner-points. We study the performance of the proposed composite descriptor. The proposed method is evaluated using Item S8 within the MPEG-7 Still Images Content Set. Experimental results show that the proposed descriptor is effective.
Image retrieval based on semantics of intra-region color properties
- Authors: Sajjanhar, Atul , Lu, Guojun , Zhang, Dengsheng , Zhou, Wanlei , Chen, Yi-Ping Phoebe
- Date: 2008
- Type: Text , Conference paper
- Relation: Proceedings of 2008 IEEE 8th International Conference on Computer and Information Technology p. 338-343
- Full Text: false
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- Description: Traditional image retrieval systems are content based image retrieval systems which rely on low-level features for indexing and retrieval of images. CBIR systems fail to meet user expectations because of the gap between the low level features used by such systems and the high level perception of images by humans. Semantics based methods have been used to describe images according to their high level features. In this paper, we performed experiments to identify the failure of existing semantics-based methods to retrieve images in a particular semantic category. We have proposed a new semantic category to describe the intra-region color feature. The proposed semantic category complements the existing high level descriptions. Experimental results confirm the effectiveness of the proposed method