Toolbox diffc: test_hessian.m - File Exchange

Code covered by the BSD License

Highlights from
Toolbox diffc

Toolbox differencial calculus...
clamp(x,a,b)
compute_crossp_vf_vf(v1,v2) compute_crossp_vf_vf - compute the crossproduct of 2 3D vector fields.
compute_deviator_tensor(T) compute_deviator_tensor - compute trace free tensor
compute_diff(x,order,options) compute_diff - compute central derivative (of order 'order') of a vector.
compute_flow(p, r, s, c, n) compute_flow - generate a flow
compute_gaussian_filter(n,s,N... compute_gaussian_filter - compute a 1D or 2D Gaussian filter.
compute_grad(M,options) compute_grad - compute the gradient of an image using central differences
compute_gradient_tensor(M,h,o... compute_gradient_tensor - compute the structure tensor
compute_hessian(M,options) compute_hessian - compute the hessian tensor field.
compute_hodge_decompositon(v,... compute_hodge_decompositon - perform Hodge decomposition of a vector field.
compute_laplacian(M,options) compute_laplacian - compute the laplacian of an image.
compute_local_maxima(M,v,d,et... compute_local_maxima - find the location of local maxima.
compute_movie_file(A, filenam... compute_movie_file - create an avi or gif file
compute_operator_1(M,par,opti... compute_operator_1 - compute a 1st order differential
compute_operator_2(M,par,opti... compute_operator_2 - compute a 2nd order differential
compute_periodic_poisson(d, s... compute_periodic_poisson - solve poisson equation
compute_rigidity_tensor(M,opt... compute_rigidity_tensor - compute the rigidity tensor field
compute_structure_tensor(M,si... compute_structure_tensor - compute the structure tensor
compute_tensor_field(n, pos,t... compute_tensor_field - compute a parametric 2D tensor field
compute_tensor_field_random(n... compute_tensor_field_random - create 2D TF
compute_vf_angle(v,dir)
compute_vf_polar_dec(vf) compute_vf_orientation - compute the polar decomposition of a vector field.
compute_vf_trajectory(points0... compute_vf_trajectory - compute the trajectories of a vector field
crop(M,n,c) crop - crop an image to reduce its size
div(Px,Py, options) div - divergence operator
getoptions(options, name, v, ... getoptions - retrieve options parameter
grad(M, options) grad - gradient, forward differences
imageplot(M,str, a,b,c) imageplot - diplay an image and a title
load_flow(name, n, options) load_flow - load a predefined flow
load_image(type, n, options) load_image - load benchmark images.
nb_dims(x) nb_dims - debugged version of ndims.
perform_angle_doubling(v,dir) perform_angle_doubling - double the angle of a vector field
perform_blurring(M, sigma, op... perform_blurring - gaussian blurs an image
perform_conjugate_gradient(A,... perform_conjugate_gradient - perform (bi)-conjugate gradient
perform_convolution(x,h, boun... perform_convolution - compute convolution with centered filter.
perform_fluid_dynamics(v,M,op... perform_fluid_dynamics - simulate a viscous fluid
perform_histogram_equalizatio... perform_histogram_equalization - perform histogram equalization
perform_image_advection(M,v, ... perform_image_advection - perform image advection along a flow
perform_orientation_diffusion... perform_orientation_diffusion - perform diffusion of orientation data
perform_tensor_decomp(T,order... perform_tensor_decomp - perform an eigendecomposition.
perform_tensor_decomp_3d(in1,... perform_tensor_decomp_3d - decompose a 3D tensor field
perform_tensor_eigendecomposi... perform_tensor_eigendecomposition - decompose a tensor field
perform_tensor_mapping(T,dir) perform_tensor_mapping - go back and forth from tensor to non-linear domain
perform_tensor_recomp(e1,e2,l... perform_tensor_recomp - create the tensor field corresponding to the given eigendecomposition.
perform_vf_integration(vf, dt... perform_vf_integration - perform a time integration of the vf
perform_vf_normalization(v) perform_v_normalization - renormalize a vector field.
perform_vf_reorientation(v, o... perform_vf_reorientation - try to reorient the vf.
plot_tensor_field(H, M, optio... plot_tensor_field - display a tensor field
plot_tensor_field(H, M, optio... plot_tensor_field - display a tensor field
plot_tf(T,M) plot_tf - plot a tensorial field.
plot_vf(vf, M, options) plot_vf - plot a vector field with
plot_vf_scaterred(vf, pos, is... plot_vf_scaterred - plot a vector field with
prod_tf_sf(T1,s) prod_tf_sf - compute the product of a tensor field by a scalar field.
prod_tf_tf(A,B) prod_tf_tf - compute the product of 2 tensor fields
prod_tf_vf(T,v) prod_vf_vf - compute the product of a tensor field and a vector field.
prod_vf_sf(v1,s) prod_vf_sf - compute the product of a vector field by a scalar field.
prod_vf_vf(v1,v2) prod_vf_vf - compute the dot product of 2 vector field.
progressbar(n,N,w) progressbar - display a progress bar
publish_html(filename, output... publish_html - publish a file to HTML format
rescale(x,a,b)
test_cg.m
test_diffc.m
test_div_grad.m
test_flow.m
test_hessian.m
test_incompressible_fluid.m
test_orientation_diffusion.m
test_singular_points.m
test_structure_tensor.m
test_tensor_3d.m
test_texture_advection.m
test_vf_integration.m
test_vf_reorientation.m
toolbox_diffc.m
View all files

from Toolbox diffc by Gabriel Peyre
A toolbox to perform differential calculus on a matrix.

test_hessian.m

% test for hessian tensor

n = 256;
name = 'barb';
M = load_image(name);
M = rescale(crop(M,n));

options.order = 2;
T = compute_hessian(M, options);

[e1,e2,l1,l2] = perform_tensor_decomp(T);
l1 = abs(l1); l2 = abs(l2);
T = perform_tensor_recomp(e1,e2,l2,l1);

sigma = 5;
T = perform_blurring(T,sigma);

options.sub = 8;
clf;
plot_tensor_field(T, M, options);
figure;
clf;
plot_tensor_field_nb(T, M, options);

Highlights from Toolbox diffc

Highlights from
Toolbox diffc