摘要:
Features are extracted from a test and reference image to generate a test and reference record. Each feature has a location, and orientation, and furthermore, the features of the reference records also have associated weights. The features of the test record are approximately aligned with the features of the reference record. Then, differences between the locations and orientations of the features of the reference record and the features of the test record are measured, and the weights of all features of the reference record that are less than a predetermined difference when compared with the features of the test record are summed to determine a similarity score that the test record matches the reference record.
摘要:
A method generates a three-dimensional, bi-linear, illumination model for arbitrary faces. A large number of images are acquired of many different faces. For each face, multiple images are acquired with varying poses and varying illumination. A three-mode singular value decomposition is applied to the images to determine parameters of the model. The model can be fit to a probe image of an unknown face. Then, the model can be compared with models of a gallery of images of unknown faces to recognize the face in the probe image.
摘要:
A method maximizes a candidate solution to a cardinality-constrained combinatorial optimization problem of sparse principal component analysis. An approximate method has as input a covariance matrix A, a candidate solution, and a sparsity parameter k. A variational renormalization for the candidate solution vector x with regards to the eigenvalue structure of the covariance matrix A and the sparsity parameter k is then performed by means of a sub-matrix eigenvalue decomposition of A to obtain a variance maximized k-sparse eigenvector x that is the best possible solution. Another method solves the problem by means of a nested greedy search technique that includes a forward and backward pass. An exact solution to the problem initializes a branch-and-bound search with an output of a greedy solution.
摘要:
A method determines a direction of a principal light source in an image. An input image I is acquired of an object illuminated by a principal light source from an unknown direction. The input image includes an array of pixels, and each pixel has an intensity I(x, y). An intensity vector {right arrow over (I)} is constructed from the intensities of the input image. An albedo map ρ is defined for the object. An albedo vector {right arrow over (ρ)} is constructed from the albedo map. A shape matrix N is generated for the object. The albedo vector {right arrow over (ρ)} is multiplied by the shape matrix N to obtain a shape-albedo matrix A. Then, a direction s* to the principal light source is estimated from the intensity vector {right arrow over (I)}, the albedo vector {right arrow over (ρ)} and the shape-albedo matrix A according to an optimization s * = arg min s I → - ρ → - As .
摘要:
A method reconstructs or synthesizes heads from 3D models of heads and 2D silhouettes of heads. A 3D statistical model is generated from multiple real human heads. The 3D statistical model includes a model parameter in the form of basis vectors and corresponding coefficients. Multiple 2D silhouettes of a particular head are acquired using a camera for example. The 3D statistical model is fitted to multiple 2D silhouettes to determine a particular value of the model parameter corresponding to the plurality of 2D silhouettes. Then, the 3D statistical model is rendered according to the particular value of the model parameter to reconstruct the particular head.
摘要:
A method recognizes a face in an image. A morphable model having shape and pose parameters is fitted to a face in an image to construct a three-dimensional model of the face. Texture is extracted from the face in the image using the three-dimensional model. The shape and texture are projected into a bilinear illumination model to generate illumination bases for the face in the image. The illumination bases for the face in the image are compared to illumination bases of each of a plurality of bilinear illumination models of known faces to identify the face in the image.
摘要:
A method determines an optimal set of viewpoints to acquire a 3D shape of a face. A view-sphere is tessellated with a plurality of viewpoint cells. The face is at an approximate center of the view-sphere. Selected viewpoint cells are discarded. The remaining viewpoint cells are clustered to a predetermined number of viewpoint cells according to a silhouette difference metric. The predetermined number of viewpoint cells are searched for a set of optimal viewpoint cells to construct a 3D model of the face.
摘要:
A method reconstructs or synthesizes heads from 3D models of heads and 2D silhouettes of heads. A 3D statistical model is generated from multiple real human heads. The 3D statistical model includes a model parameter in the form of basis vectors and corresponding coefficients. Multiple 2D silhouettes of a particular head are acquired using a camera for example. The 3D statistical model is fitted to multiple 2D silhouettes to determine a particular value of the model parameter corresponding to the plurality of 2D silhouettes. Then, the 3D statistical model is rendered according to the particular value of the model parameter to reconstruct the particular head.
摘要:
A method determines a direction of a principal light source in an image. An input image I is acquired of an object illuminated by a principal light source from an unknown direction. The input image includes an array of pixels, and each pixel has an intensity I(x, y). An intensity vector {right arrow over (I)} is constructed from the intensities of the input image. An albedo map ρ is defined for the object. An albedo vector {right arrow over (ρ)} is constructed from the albedo map. A shape matrix N is generated for the object. The albedo vector {right arrow over (ρ)} is multiplied by the shape matrix N to obtain a shape-albedo matrix A. Then, a direction s* to the principal light source is estimated from the intensity vector {right arrow over (I)}, the albedo vector {right arrow over (ρ)} and the shape-albedo matrix A according to an optimization s * = arg min s I → - ρ → - As .
摘要:
A method classifies images of faces according to gender. Training images of male and female faces are supplied to a vector support machine. A small number of support vectors are determined from the training images. The support vectors identify a hyperplane. After training, a test image is supplied to the support vector machine. The test image is classified according to the gender of the test image with respect to the hyperplane.