ImageDev

OpeningLine3d

Performs a three-dimensional opening using a structuring element matching with a line.

Access to parameter description

For an introduction: This algorithm successively runs an ErosionLine3d and a DilationLine3d with the same kernel in the opposite direction. A linear opening controls the direction of the opening, therefore making it possible to remove objects and isthmi thinner than the structuring element in its direction.
The erosion line is oriented in the direction given by ($\theta$, $\varphi$) in spherical coordinates as often used in mathematics (azimuthal angle, $\theta$ and polar angle, $\varphi$). This direction is described with the following formula: $$V=\left[\begin{array}{c}; v_x\\ v_y\\ v_z\end{array}\right] = \left[\begin{array}{c}; \sin(\varphi)\cos(\theta)\\ \sin(\varphi)\sin(\theta)\\ \cos(\varphi)\end{array}\right]$$ This direction can be illustrated on the unit sphere:

<b> Figure 1.</b> Azimuthal and polar angles on the unit sphere
Figure 1. Azimuthal and polar angles on the unit sphere

With a classic implementation, morphological opening systematically considers areas out of the image as a replication of the image borders at each step of the algorithm. Therefore, when applying an opening, some thin object parts cut by the image borders may be removed at the erosion step and not be restored after the dilation, while one would expect to keep them. The borderPolicy parameter manages this case. The default mode, LIMITED, corresponds to the classic behavior. The EXTENDED mode properly manages image borders by extending them by a size equal to the structuring element's. This mode can be slower and more memory consuming, especially when the structuring element size is high.
This option is illustrated in the Opening2d documentation (Figure 2).

See also

Function Syntax

This function returns outputImage. 
// Function prototype
std::shared_ptr< iolink::ImageView >
openingLine3d( std::shared_ptr< iolink::ImageView > inputImage,
               double thetaAngle,
               double phiAngle,
               uint32_t kernelRadius,
               OpeningLine3d::BorderPolicy borderPolicy,
               std::shared_ptr< iolink::ImageView > outputImage = NULL );
This function returns outputImage. 
// Function prototype.
opening_line_3d( input_image,
                 theta_angle = 0,
                 phi_angle = 0,
                 kernel_radius = 3,
                 border_policy = OpeningLine3d.BorderPolicy.LIMITED,
                 output_image = None )
This function returns outputImage. 
// Function prototype.
public static IOLink.ImageView
OpeningLine3d( IOLink.ImageView inputImage,
               double thetaAngle = 0,
               double phiAngle = 0,
               UInt32 kernelRadius = 3,
               OpeningLine3d.BorderPolicy borderPolicy = ImageDev.OpeningLine3d.BorderPolicy.LIMITED,
               IOLink.ImageView outputImage = null );

Class Syntax

Parameters

Class Name OpeningLine3d

Parameter Name Description Type Supported Values Default Value
input
inputImage
The input image. The image type can be integer or float. Image Binary, Label, Grayscale or Multispectral nullptr
input
borderPolicy
The border policy to apply.
LIMITED The limited mode is faster to compute, but can produce the unexpected results for particles close to the image border.
EXTENDED The Extended mode is slower to compute, but produces the expected results for particles close to the image border.
Enumeration LIMITED
input
thetaAngle
The azimuthal angle in degrees. Float64 Any value 0
input
phiAngle
The polar angle in degrees. Float64 Any value 0
input
kernelRadius
The length of the linear structuring element in voxels. UInt32 >=1 3
output
outputImage
The output image. Its dimensions and type are forced to the same values as the input image. Image nullptr

Object Examples

auto foam = readVipImage( std::string( IMAGEDEVDATA_IMAGES_FOLDER ) + "foam.vip" );

OpeningLine3d openingLine3dAlgo;
openingLine3dAlgo.setInputImage( foam );
openingLine3dAlgo.setThetaAngle( 0 );
openingLine3dAlgo.setPhiAngle( 0 );
openingLine3dAlgo.setKernelRadius( 3 );
openingLine3dAlgo.setBorderPolicy( OpeningLine3d::BorderPolicy::EXTENDED );
openingLine3dAlgo.execute();

std::cout << "outputImage:" << openingLine3dAlgo.outputImage()->toString();

foam = imagedev.read_vip_image(imagedev_data.get_image_path("foam.vip"))

opening_line_3d_algo = imagedev.OpeningLine3d()
opening_line_3d_algo.input_image = foam
opening_line_3d_algo.theta_angle = 0
opening_line_3d_algo.phi_angle = 0
opening_line_3d_algo.kernel_radius = 3
opening_line_3d_algo.border_policy = imagedev.OpeningLine3d.EXTENDED
opening_line_3d_algo.execute()

print( "output_image:", str( opening_line_3d_algo.output_image ) )

ImageView foam = Data.ReadVipImage( @"Data/images/foam.vip" );

OpeningLine3d openingLine3dAlgo = new OpeningLine3d
{
    inputImage = foam,
    thetaAngle = 0,
    phiAngle = 0,
    kernelRadius = 3,
    borderPolicy = OpeningLine3d.BorderPolicy.EXTENDED
};
openingLine3dAlgo.Execute();

Console.WriteLine( "outputImage:" + openingLine3dAlgo.outputImage.ToString() );

Function Examples

auto foam = readVipImage( std::string( IMAGEDEVDATA_IMAGES_FOLDER ) + "foam.vip" );

auto result = openingLine3d( foam, 0, 0, 3, OpeningLine3d::BorderPolicy::EXTENDED );

std::cout << "outputImage:" << result->toString();

foam = imagedev.read_vip_image(imagedev_data.get_image_path("foam.vip"))

result = imagedev.opening_line_3d( foam, 0, 0, 3, imagedev.OpeningLine3d.EXTENDED )

print( "output_image:", str( result ) )

ImageView foam = Data.ReadVipImage( @"Data/images/foam.vip" );

IOLink.ImageView result = Processing.OpeningLine3d( foam, 0, 0, 3, OpeningLine3d.BorderPolicy.EXTENDED );

Console.WriteLine( "outputImage:" + result.ToString() );