derivate_gauss — Convolve an image with derivatives of the Gaussian.
derivate_gauss convolves an image with the derivatives of a Gaussian and calculates various features derived therefrom. Sigma is the parameter of the Gaussian (i.e., the amount of smoothing). If one value is passed in Sigma the amount of smoothing in the column and row direction is identical. If two values are passed in Sigma the first value specifies the amount of smoothing in the column direction, while the second value specifies the amount of smoothing in the row direction. The possible values for Component are:
First derivative along x.
First derivative along y.
Absolute value of the gradient.
Gradient direction in radians.
Second derivative along x.
Second derivative along y.
Second derivative along x and y.
Third derivative along x.
Third derivative along y.
Third derivative along x, x and y.
Third derivative along x, y and y.
Determinant of the Hessian matrix:
Laplace operator (trace of the Hessian matrix):
Mean curvature H
Gaussian curvature K
Differential Area A
Direction of the eigenvector corresponding to the first eigenvalue in radians
Second derivative perpendicular to the gradient
Normalized second derivative perpendicular to the gradient
Second derivative along the gradient
Second derivative along and perpendicular to the gradient
Note that filter operators may return unexpected results if an image with a reduced domain is used as input. Please refer to the chapter Filters.
Filtered result images.
Sigma of the Gaussian.
Default value: 1.0
Suggested values: 0.7, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0
Typical range of values: 0.2 ≤ Sigma ≤ 50.0
Minimum increment: 0.01
Recommended increment: 0.1
Restriction: 0.01 <= Sigma <= 50.0
Derivative or feature to be calculated.
Default value: 'x'
List of values: '2nd_ddg', 'area', 'de_saint_venant', 'det', 'eigenvalue1', 'eigenvalue2', 'eigenvec_dir', 'gauss_curvature', 'gradient', 'gradient_dir', 'kitchen_rosenfeld', 'laplace', 'main1_curvature', 'main2_curvature', 'mean_curvature', 'none', 'x', 'xx', 'xxx', 'xxy', 'xy', 'xyy', 'y', 'yy', 'yyy', 'zuniga_haralick'
List of values (for compute devices): 'none', 'x', 'y', 'gradient', 'gradient_dir', 'xx', 'yy', 'xy', 'xxx', 'yyy', 'xxy', 'xyy', 'laplace'
read_image(&Image,"mreut"); derivate_gauss(Image,&Gauss,3.0,"x"); zero_crossing(Gauss,&ZeroCrossings);
laplace, laplace_of_gauss, binomial_filter, gauss_filter, smooth_image, isotropic_diffusion