xGradImg,yGradImg,zGradImg =	sobelGradient3dImg (inImg)
xGradImg,yGradImg,zGradImg =	sobelGradient3dImg (inImg,kernelType,bNormalize)
image =	sobelXGradient3dImg (inImg)
image =	sobelXGradient3dImg (inImg,kernelType,bNormalize)
image =	sobelYGradient3dImg (inImg)
image =	sobelYGradient3dImg (inImg,kernelType,bNormalize)
image =	sobelZGradient3dImg (inImg)
image =	sobelZGradient3dImg (inImg,kernelType,bNormalize)

Detailed Description

Compute X, Y and Z gradients of an input image convolving it with 3d Sobel kernels.

3d Sobel kernels are separable, they can be decomposed as the product of 3 vectors. X gradient kernel equals to the product $V_{smoothing}*V_{smoothing}*V_{deriv}$ , Y gradient kernel equals to the product $V_{smoothing}*V_{deriv}*V_{smoothing}$ , and Z gradient kernel equals to the product $V_{deriv}*V_{smoothing}*V_{smoothing}$ . Depending on the value of parameter $InOptSobelKernelType$ (default value: eSKT_SobelHalfKnlSz1), smoothing and derivative vectors equal to:

$V_{smoothing}=\begin{bmatrix} 1 & 2 & 1 \end{bmatrix}$ , $V_{deriv}=\begin{bmatrix} -1 & 0 & 1 \end{bmatrix}$ if equals to eSKT_SobelHalfKnlSz1
$V_{smoothing}=\begin{bmatrix} 3 & 10 & 3 \end{bmatrix}$ , $V_{deriv}=\begin{bmatrix} -1 & 0 & 1 \end{bmatrix}$ if equals to eSKT_ScharrHalfKnlSz1
$V_{smoothing}=\begin{bmatrix} 1 & 4 & 6 & 4 & 1 \end{bmatrix}$ , $V_{deriv}=\begin{bmatrix} -1 & -2 & 0 & 2 & 1 \end{bmatrix}$ if equals to eSKT_SobelHalfKnlSz2
$V_{smoothing}=\begin{bmatrix} 1 & 6 & 15 & 20 & 15 & 6 & 1 \end{bmatrix}$ , $V_{deriv}=\begin{bmatrix} -1 & -4 & -5 & 0 & 5 & 4 & 1 \end{bmatrix}$ if equals to eSKT_SobelHalfKnlSz3

has the default value . When the user sets this parameter to the value , only the smoothing part of the 2d kernel is normalized.

To handle image borders, a mirror extrapolation is used (see Border policy for more details).

Here is an example of a Sobel gradient applied to an 8-bits grey levels input image with default parameters used:

See also: https://en.wikipedia.org/wiki/Sobel_operator

Example of Python code :

Example imports

import PyIPSDK

import PyIPSDK.IPSDKIPLFiltering as filter

Code Example

    # opening of input images
    inImg = PyIPSDK.loadTiffImageFile(inputImgPath)
    
    # Sobel gradient filter 3d computation
    outGxImg,  outGyImg,  outGzImg = filter.sobelGradient3dImg(inImg)

Example of C++ code :

Example informations

Header file

#include <IPSDKIPL/IPSDKIPLFiltering/Processor/SobelGradient3dImg/SobelGradient3dImg.h>

Code Example

    // opening input 3D image from TIFF file
    ImagePtr pInImg = loadTiffImageFile(inputImgPath, eTiffDirectoryMode::eTDM_Volume);
    // applying Sobel gradient to input image
    GradientXYZImg gradientXYZ = sobelGradient3dImg(pInImg);