Laplacian filter

Figure 6 UVP data (a) raw velocity data, (b) data using a Laplacian filter, (c) data using a forward differentiation filter, (d) data using a Sobel filter, (e) binarized Sobel data, and (f) gas-phase detected after the application of the Sobel filter.

The Laplacian filter is a special high pass filter, effectively enhancing the plume and other subtle sensor noise in the image. A Laplacian convolution mask is applied to perform edge enhancement and is insensitive to direction and invariant to rotation. 

There are two steps involved in palm tree counting. The first step is the selective smoothing by non-linear diffusion, which results in a sharp contrast among a number of different features followed by Laplacian filtering. 

The second step is Laplacian filtering which can be suggested as an irreducible differential invariant. It is expressed mathematically by equation... 

Figure 8.27. Steps preceding the computation of a CDF with fiber symmetry from recorded raw data The image is projected on the fiber plane, the equivalent of the Laplacian in real space is applied, the background is determined by low-pass filtering. After background subtraction the interference function is received... 

Figure 5 Filters applied to the UVP velocity values (a) Laplacian, (b) forward differentiation, and (c) Sobel.

Within the framework of scale-space filtering, inflexion points of F(t) appear as extrema in dF(t)/dt and zero crossings in d2F(t)/dt2. Thus, filtering a signal by the Laplacian (second derivative) of a Gaussian will generate the inflexion points at various scales (Marr and Hildreth, 1980). In the same spirit, if the wavelet is chosen to be the first derivative of a scaling function, i.e., ip(t) = d(t)/ dt, then from Eqs. (5a) and (11) we... 

Fig. 8. Binarization example in top row (a) original image, (b) Otsu method, (c) filtering with Laplacian operator, and (d) its binarization with Otsu in bottom row (e) SOM, (f) MSCL in homogeneous grey quantization, (g) MSCL with two features, and (h) Otsu binarization of (g).

Researchers started to develop algorithms and application software to count trees [69-71], In this communication, selective filtering and Laplacian blob are used for classifying date pahn trees in both the urban and agricultural areas. 

Multi-spectral classification Laplacian maxima filtering ... 

The contourlet transform utilizes a Laplacian pyramid to capture point discontinuities. In addition, it uses directional filter banks to relate point discontinuities into linear structures. However, the non-subsampled process in the contourlet transform causes... 

When using the Laplacian of Gaussian approach, edges are detected at a particular resolution (scale) depending on the spread of the Gaussian filter used. 

Filtering image for visualization or post-processing conveniently. These filters are Edge Extraction (Sobel), Sharpen, Low-pass, High-pass, Laplacian. 

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