Thresholding

Transforms a grayscale image into a binary image where all pixels with an initial gray level value lying between two user-defined bounds are set to 1 and all others are set to 0.

Access to parameter description

For an introduction:

• section Image Segmentation
• section Binarization

This algorithm produces a binary image representing, in its foreground, data between two gray levels $\lambda_1$ and $\lambda_2$.
Threshold with 2 bounds is the default behavior, but a threshold with a single bound may be achieved by setting $\lambda_1$ or $\lambda_2$ to the minimum or maximum value of the input data range (for example, 0 or 255, respectively for 8-bit unsigned data).

The definition is: $$ O(n,m)=\left\{\begin{array}{ll} 1 & \mbox{if } \lambda_1 \leq I(n,m) \leq \lambda_2 \\ 0 & \mbox{if I(n,m) <} \lambda_1 \mbox{ or I(n,m)>} \lambda_2 \end{array}\right. $$

Note: This algorithm is dedicated to be applied on grayscale images. However, for convenience, it does not return an exception when applied on a color image. It simply processes the last color channel; for instance, the blue channel in the case of an RGB image.

See also

• ThresholdingByCriterion
• AutoThresholdingBright
• ColorThresholding

See related example

• Thresholding

// Function prototype.
std::shared_ptr< iolink::ImageView >
thresholding( std::shared_ptr< iolink::ImageView > inputImage,
              iolink::Vector2d thresholdRange,
              std::shared_ptr< iolink::ImageView > outputBinaryImage = NULL );

// Function prototype.
thresholding( input_image, threshold_range = [128, 255], output_binary_image = None )

// Function prototype.
public static IOLink.ImageView
Thresholding( IOLink.ImageView inputImage,
              double[] thresholdRange = null,
              IOLink.ImageView outputBinaryImage = null );

// Command constructor.
Thresholding();

// 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 thresholdRange parameter.
iolink::Vector2d thresholdRange() const;
// Set method of the thresholdRange parameter.
void setThresholdRange( const iolink::Vector2d& thresholdRange );

// 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.
Thresholding.input_image
// Property of the thresholdRange parameter.
Thresholding.threshold_range
// Property of the outputBinaryImage parameter.
Thresholding.output_binary_image

// Method to launch the command.
execute()

// Command constructor.
Thresholding()

// Property of the inputImage parameter.
Thresholding.inputImage
// Property of the thresholdRange parameter.
Thresholding.thresholdRange
// Property of the outputBinaryImage parameter.
Thresholding.outputBinaryImage

// Method to launch the command.
Execute()

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

Thresholding thresholdingAlgo;
thresholdingAlgo.setInputImage( foam );
thresholdingAlgo.setThresholdRange( {128.0, 255.0} );
thresholdingAlgo.execute();

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

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

thresholding_algo = imagedev.Thresholding()
thresholding_algo.input_image = foam
thresholding_algo.threshold_range = [128.0, 255.0]
thresholding_algo.execute()

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

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

Thresholding thresholdingAlgo = new Thresholding
{
    inputImage = foam,
    thresholdRange = new double[]{128.0, 255.0}
};
thresholdingAlgo.Execute();

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

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

auto result = thresholding( foam, {128.0, 255.0} );

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

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

result = imagedev.thresholding( foam, [128.0, 255.0] )

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

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

IOLink.ImageView result = Processing.Thresholding( foam, new double[]{128.0, 255.0} );

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