Bezier curve-based generic shape encoder
- Authors: Sohel, Ferdous , Karmakar, Gour , Dooley, Laurence , Bennamoun, M.
- Date: 2010
- Type: Text , Journal article
- Relation: IET Image Processing Vol. 4, no. 2 (2010), p. 92-102
- Full Text: false
- Reviewed:
- Description: Existing Bezier curve-based shape description techniques primarily focus upon determining a set of pertinent control points (CP) to represent a particular shape contour. While many different approaches have been proposed, none adequately consider domain-specific information about the shape contour like its gradualness and sharpness, in the CP generation process which can potentially result in large distortions in the object's shape representation. This study introduces a novel Bezier curve-based generic shape encoder (BCGSE) that partitions an object contour into contiguous segments based upon its cornerity, before generating the CP for each segment using relevant shape curvature information. In addition, although CP encoding has generally been ignored, BCGSE embeds an efficient vertex-based encoding strategy exploiting the latent equidistance between consecutive CP. A non-linear optimisation technique is also presented to enable the encoder is automatically adapt to bit-rate constraints. The performance of the BCGSE framework has been rigorously tested on a variety of diverse arbitrary shapes from both a distortion and requisite bit-rate perspective, with qualitative and quantitative results corroborating its superiority over existing shape descriptors.
Geometric distortion measurement for shape coding: a contemporary review
- Authors: Sohel, Ferdous , Karmakar, Gour , Dooley, Laurence , Bennamoun, M.
- Date: 2011
- Type: Text , Journal article
- Relation: ACM Computing Surveys Vol. 43, no. 4 (2011), p. 1-22
- Full Text: false
- Reviewed:
- Description: Geometric distortion measurement and the associated metrics involved are integral to the Rate Distortion (RD) shape coding framework, with importantly the efficacy of the metrics being strongly influenced by the underlying measurement strategy. This has been the catalyst for many different techniques with this article presenting a comprehensive review of geometric distortion measurement, the diverse metrics applied, and their impact on shape coding. The respective performance of these measuring strategies is analyzed from both a RD and complexity perspective, with a recent distortion measurement technique based on arc-length-parameterization being comparatively evaluated. Some contemporary research challenges are also investigated, including schemes to effectively quantify shape deformation.
Sliding-window designs for vertex-based shape coding
- Authors: Sohel, Ferdous , Karmakar, Gour , Dooley, Laurence , Bennamoun, M.
- Date: 2012
- Type: Text , Journal article
- Relation: IEEE Transactions on Multimedia Vol. 14, no. 3 (June 2012), p. 683-692
- Full Text: false
- Reviewed:
- Description: Traditionally the sliding window (SW) has been employed in vertex-based operational rate distortion (ORD) optimal shape coding algorithms to ensure consistent distortion (quality) measurement and improve computational efficiency. It also regulates the memory requirements for an encoder design enabling regular, symmetrical hardware implementations. This paper presents a series of new enhancements to existing techniques for determining the best SW-length within a rate-distortion (RD) framework, and analyses the nexus between SW-length and storage for ORD hardware realizations. In addition, it presents an efficient bit-allocation strategy for managing multiple shapes together with a generalized adaptive SW scheme which integrates localized curvature information (cornerity) on contour points with a bi-directional spatial distance, to afford a superior and more pragmatic SW design compared with existing adaptive SW solutions which are based on only cornerity values. Experimental results consistently corroborate the effectiveness of these new strategies.