LoG-Operator (Laplace of Gaussian).
laplace_of_gauss calculates the Laplace-of-Gaussian operator, i.e., the Laplace operator on a Gaussian smoothed image, for arbitrary smoothing parameters Sigma. The Laplace operator is given by:
2 2 __ d d \/ g(x,y)) = --- g(x,y) + --- g(x,y) 2 2 dx dyThe derivatives in laplace_of_gauss are calculated by appropriate derivatives of the Gaussian, resulting in the following formula for the convolution mask:
/ 2 2 \ / 2 2 \ __ 1 | x + y | | x + y | \/ G (x,y) = ------- | ------ - 1 | exp | - ------ | s 4 | 2 | | 2 | 2 pi s \ 2 s / \ 2 s /
Image (input_object) |
image(-array) -> object : byte / int1 / int2 / int4 / real |
Input image. |
ImageLaplace (output_object) |
image(-array) -> object : int2 |
Laplace filtered image. |
Sigma (input_control) |
number -> real / integer |
Smoothing parameter of the Gaussian. | |
Default value: 2.0 | |
Suggested values: 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.0 | |
Range of values: 0.2 <= Sigma <= 20.0 | |
Minimum increment: 0.01 | |
Recommended increment: 0.1 | |
Restriction: Sigma > 0.0 |
read_image(&Image,"mreut"); laplace_of_gauss(Image,&Laplace,2.0); zero_crossing2(Laplace,&ZeroCrossings);
zero_crossing1, zero_crossing2
laplace__, diff_of_gauss__, derivate_gauss