Face segmentation is one of the most important tasks in Model Based Video coding for Video Telephony and Video Conferencing applications. Since the face movement is usually different from the back ground movement, gradient of the optical flow field gives useful hints for the region of the image frame containing human face. In this work we have used a modified GVF-Snake (Gradient Vector Flow-Sna...

introduction 3d reconstruction of an object from its 2d cross-sections (slices) has many applications in different fields of sciences such as medical physics and biomedical engineering. in order to perform 3d reconstruction, at first, desired boundaries at each slice are detected and then using a correspondence between points of successive slices surface of desired object is reconstructed. mate...

We propose a novel external force for active contours, which we call neighborhood-extending and noise-smoothing gradient vector flow (NNGVF). The proposed NNGVF snake expresses the gradient vector flow (GVF) as a convolution with a neighborhood-extending Laplacian operator augmented by a noise-smoothing mask. We find that the NNGVF snake provides better segmentation than the GVF snake in terms ...

In this paper constrained Gradient Vector Flow (GVF) field generation is performed, for fast and accurate unsupervised stereoscopic semantic segmentation. The scheme utilizes the information provided by a depth segments map, produced by stereo analysis methods and incorporation of a segmentation algorithm. Then a Canny edge detector is applied to the depth region and produces an edge map. The e...

This paper presents a novel variational and Partial Differential Equation (PDE)based method to link edge points into closed contours. First, an ending point restrained energy function, which improves the one used in the Gradient Vector Flow (GVF) Snake model, is proposed to derive an ending point restrained Gradient Vector Flow (ERGVF) field. When there are broken edges in the edge map, the GVF...

In this study, we discover some deficiencies of GVF and GGVF Snake such as it can not capture boundaries like “U” and “S” completely because of the counteraction of some external forces and the influence of the local minimum external forces. Based on analyzing force distribution rules of gradient vector flow, a standard is introduced to distinguish every control point is true or false. An addit...

This article deals with the so called GVF (Gradient Vector Flow) introduced by C. Xu, J.L. Prince [14, 15]. We give existence and uniqueness results for the front propagation flow for boundary extraction that was initiated by Paragios, Mellina-Gottardo et Ralmesh [11, 12]. The model combines the geodesic active contour flow and the GVF to determine the geometric flow. The motion equation is con...

Active contours, or snakes, are used extensively in computer vision and image processing applications, particularly to locate object boundaries. A new type of external force for active contours, called gradient vector flow (GVF) was introduced recently to address problems associated with initialization and poor convergence to boundary concavities. GVF is computed as a diffusion of the gradient ...

Transfer function is very important for volume rendering. One common approach is to map the gradient magnitude to opacity transfer functions. However, it catches too many small details. Gradient vector flow (GVF) vectors have large magnitudes in the immediate vicinity of the edges, where the GVF vectors keep coordinate with the vectors of the gradient of the edge map. While in homogeneous regio...

We present an active surface model designed for the segmentation of Drosophila Schneider cell nuclei and nucleoli from wide-field microscopic data. The imaging technique as well as the biological application impose some major challenges to the segmentation. On the one hand, we have to deal with strong blurring of the 3D data, especially in z-direction. On the other hand, concerning the biologic...