DobFilter2d

Appproximates a Laplacian as the difference of two box filters applied on the same two-dimensional image.

Access to parameter description

For an introduction:

• section Edge Detection
• section Laplacian
• section Images Filters

DobFilter2d calculates the difference between two local averages computed over square neighborhoods of different kernel sizes (Difference Of Boxes) applied on the same image. The operation consists of the same filter performed with two different kernel sizes.
The size of the kernels must be an odd number.

This operation applied to a 1D step edge is shown in Figure 1.

DobFilter2d does not compute the Laplacian of an image, but is a good approximation and has the main advantage of not generating isolated points.

Typical ratios of the neighborhood sizes (width of Box1 / width of Box2) has a range between 1.5 and 2.5. Box1 and Box2 are respectively parametrized by the parameters largeBoxSize and smallBoxSize.
For example, kernels of size 5x5/3x3 or 9x9/5x5 can be used.

To keep a correct representation of the edges and a maximum of detail, using too large a kernel is not recommended (3, 5 and 7 are the most frequent values).

The deviation between the two masks has a direct effect on the edges. If the difference is too large, the edges are very thick and all small details disappear. If the difference is small (less than 4), the edges are very thin and details more precise.

See also

• DobFilter3d
• RecursiveLaplacian2d

// Function prototype.
std::shared_ptr< iolink::ImageView >
dobFilter2d( std::shared_ptr< iolink::ImageView > inputImage,
             int32_t smallBoxSize,
             int32_t largeBoxSize,
             std::shared_ptr< iolink::ImageView > outputImage = NULL );

// Function prototype.
dob_filter_2d( input_image,
               small_box_size = 3,
               large_box_size = 7,
               output_image = None )

// Function prototype.
public static IOLink.ImageView
DobFilter2d( IOLink.ImageView inputImage,
             Int32 smallBoxSize = 3,
             Int32 largeBoxSize = 7,
             IOLink.ImageView outputImage = null );

// Command constructor.
DobFilter2d();

// 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 smallBoxSize parameter.
int32_t smallBoxSize() const;
// Set method of the smallBoxSize parameter.
void setSmallBoxSize( const int32_t& smallBoxSize );

// Get method of the largeBoxSize parameter.
int32_t largeBoxSize() const;
// Set method of the largeBoxSize parameter.
void setLargeBoxSize( const int32_t& largeBoxSize );

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

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

// Property of the inputImage parameter.
DobFilter2d.input_image
// Property of the smallBoxSize parameter.
DobFilter2d.small_box_size
// Property of the largeBoxSize parameter.
DobFilter2d.large_box_size
// Property of the outputImage parameter.
DobFilter2d.output_image

// Method to launch the command.
execute()

// Command constructor.
DobFilter2d()

// Property of the inputImage parameter.
DobFilter2d.inputImage
// Property of the smallBoxSize parameter.
DobFilter2d.smallBoxSize
// Property of the largeBoxSize parameter.
DobFilter2d.largeBoxSize
// Property of the outputImage parameter.
DobFilter2d.outputImage

// Method to launch the command.
Execute()

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

DobFilter2d dobFilter2dAlgo;
dobFilter2dAlgo.setInputImage( polystyrene );
dobFilter2dAlgo.setSmallBoxSize( 3 );
dobFilter2dAlgo.setLargeBoxSize( 7 );
dobFilter2dAlgo.execute();

std::cout << "outputImage:" << dobFilter2dAlgo.outputImage()->toString();

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

dob_filter_2d_algo = imagedev.DobFilter2d()
dob_filter_2d_algo.input_image = polystyrene
dob_filter_2d_algo.small_box_size = 3
dob_filter_2d_algo.large_box_size = 7
dob_filter_2d_algo.execute()

print( "output_image:", str( dob_filter_2d_algo.output_image ) )

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

DobFilter2d dobFilter2dAlgo = new DobFilter2d
{
    inputImage = polystyrene,
    smallBoxSize = 3,
    largeBoxSize = 7
};
dobFilter2dAlgo.Execute();

Console.WriteLine( "outputImage:" + dobFilter2dAlgo.outputImage.ToString() );

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

auto result = dobFilter2d( polystyrene, 3, 7 );

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

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

result = imagedev.dob_filter_2d( polystyrene, 3, 7 )

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

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

IOLink.ImageView result = Processing.DobFilter2d( polystyrene, 3, 7 );

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