ZeroCrossings2d

Thresholds pixels where the sign of a Laplacian image changes.

Access to parameter description

For an introduction:

• section Laplacian
• section Edge Marking

Zero-crossings are points where the Laplacian switches from positive to negative values, and vice versa.

A simple zero-crossing detection is obtained by thresholding the Laplacian to retain positive intensities, then detecting the boundaries of the binary image, as shown in Figure 1. Such zero-crossing points are not precisely located.


Zero-crossing is even better to mark a point if the Laplacian changes its sign in its 3x3 neighbourhood, and if the Laplacian magnitude is smaller than all magnitudes in that neighbourhood, as shown in Figure 2.


Compared to thresholding of a gradient, zero-crossings have the advantage of producing closed curves of 1 pixel thickness. This is most interesting when precise object boundary detection is the goal.
See also

• RecursiveLaplacian2d
• ImageLocalMaxima2d

// Function prototype.
std::shared_ptr< iolink::ImageView >
zeroCrossings2d( std::shared_ptr< iolink::ImageView > inputImage, std::shared_ptr< iolink::ImageView > outputBinaryImage = NULL );

// Function prototype.
zero_crossings_2d( input_image, output_binary_image = None )

// Function prototype.
public static IOLink.ImageView
ZeroCrossings2d( IOLink.ImageView inputImage, IOLink.ImageView outputBinaryImage = null );

// Command constructor.
ZeroCrossings2d();

// Get method of the inputImage parameter.
std::shared_ptr< iolink::ImageView > inputImage() const;
// Set method of the inputImage parameter.
void setInputImage( std::shared_ptr< iolink::ImageView > inputImage );

// Get method of the outputBinaryImage parameter.
std::shared_ptr< iolink::ImageView > outputBinaryImage() const;
// Set method of the outputBinaryImage parameter.
void setOutputBinaryImage( std::shared_ptr< iolink::ImageView > outputBinaryImage );

// Method to launch the command.
void execute();

// Property of the inputImage parameter.
ZeroCrossings2d.input_image
// Property of the outputBinaryImage parameter.
ZeroCrossings2d.output_binary_image

// Method to launch the command.
execute()

// Command constructor.
ZeroCrossings2d()

// Property of the inputImage parameter.
ZeroCrossings2d.inputImage
// Property of the outputBinaryImage parameter.
ZeroCrossings2d.outputBinaryImage

// Method to launch the command.
Execute()

std::shared_ptr< iolink::ImageView > polystyrene = ioformat::readImage( std::string( IMAGEDEVDATA_IMAGES_FOLDER ) + "polystyrene.tif" );

ZeroCrossings2d zeroCrossings2dAlgo;
zeroCrossings2dAlgo.setInputImage( polystyrene );
zeroCrossings2dAlgo.execute();

std::cout << "outputBinaryImage:" << zeroCrossings2dAlgo.outputBinaryImage()->toString();

polystyrene = ioformat.read_image(imagedev_data.get_image_path("polystyrene.tif"))

zero_crossings_2d_algo = imagedev.ZeroCrossings2d()
zero_crossings_2d_algo.input_image = polystyrene
zero_crossings_2d_algo.execute()

print( "output_binary_image:", str( zero_crossings_2d_algo.output_binary_image ) );

ImageView polystyrene = ViewIO.ReadImage( @"Data/images/polystyrene.tif" );

ZeroCrossings2d zeroCrossings2dAlgo = new ZeroCrossings2d
{
    inputImage = polystyrene
};
zeroCrossings2dAlgo.Execute();

Console.WriteLine( "outputBinaryImage:" + zeroCrossings2dAlgo.outputBinaryImage.ToString() );

std::shared_ptr< iolink::ImageView > polystyrene = ioformat::readImage( std::string( IMAGEDEVDATA_IMAGES_FOLDER ) + "polystyrene.tif" );

auto result = zeroCrossings2d( polystyrene );

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

polystyrene = ioformat.read_image(imagedev_data.get_image_path("polystyrene.tif"))

result = imagedev.zero_crossings_2d( polystyrene )

print( "output_binary_image:", str( result ) );

ImageView polystyrene = ViewIO.ReadImage( @"Data/images/polystyrene.tif" );

IOLink.ImageView result = Processing.ZeroCrossings2d( polystyrene );

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