Where does BinaryThresholdFilter live in the IronBarcode API?

BinaryThresholdFilter is a class in the IronBarCode namespace, shipped in IronBarCode.dll. It derives from Object and implements IImageFilter, so it can be added to the ImageFilterCollection assigned to BarcodeReaderOptions.ImageFilters.

What is the difference between BinaryThresholdFilter and AdaptiveThresholdFilter?

BinaryThresholdFilter applies one global cutoff across the whole image and works best when lighting is even. AdaptiveThresholdFilter computes a separate cutoff per region, which handles uneven illumination and shadows that a single threshold cannot.

How do you set the threshold for BinaryThresholdFilter in C#?

Pass a Threshold value to one of the constructor overloads, or set the Threshold property after construction. Lower and Upper choose the two output colors, and BinarizationMethod selects the split algorithm. The defaults suit most evenly lit images.

Class BinaryThresholdFilter

A filter to binarize an image.

Inheritance

System.Object

BinaryThresholdFilter

Implements

IImageFilter

Namespace: IronBarCode

Assembly: IronBarCode.dll

Syntax

public class BinaryThresholdFilter : Object, IImageFilter

A hard two-tone conversion of a barcode image, where every pixel becomes either black or white at a chosen luminance cutoff, is the job of BinaryThresholdFilter. It splits the pixels at a single global threshold by comparing the luminance of each color component, which is the fast, predictable way to flatten a evenly lit but low-contrast image into the crisp bars a decoder expects. Where AdaptiveThresholdFilter computes a cutoff per region for patchy lighting, this filter uses one cutoff across the whole frame, so it suits images whose brightness is consistent and only the contrast is weak.

The filter implements IImageFilter and is added to the ImageFilterCollection on BarcodeReaderOptions.ImageFilters. Because the reader applies the collection in order before decoding, a binary threshold usually runs early, turning the source into a clean black-and-white image that any later step works from. A developer instantiates it, adds it to the collection, and hands the options to BarcodeReader.Read.

The constructors range from a parameterless default to overloads that take a Threshold, the Lower and Upper colors, a Rectangle region, and a BinarizationMethod. The Threshold property is the cutoff luminance, Lower and Upper set the two colors pixels collapse to, Rectangle confines the operation to a region of interest, and BinarizationMethod selects the algorithm used to decide the split. IronBarcode ships sensible defaults for every property, so a bare new BinaryThresholdFilter() is often enough; reach for the overloads only when a specific image needs a tuned cutoff or a restricted region.

using IronBarCode;

var options = new BarcodeReaderOptions
{
    ImageFilters = new ImageFilterCollection { new BinaryThresholdFilter() }
};
var results = BarcodeReader.Read("low-contrast.png", options);

The image correction how-to compares this filter against the adaptive threshold on a real barcode, and the imperfect barcode example reads a degraded image end to end. The image orientation correction how-to covers the rotation and skew cases a threshold pass does not address.

Constructors

BinaryThresholdFilter()

Initializes a new instance of the BinaryThresholdFilter class.

Declaration

public BinaryThresholdFilter()

BinaryThresholdFilter(BinarizationMethod)

Initializes a new instance of the BinaryThresholdFilter class with the specified threshold and binarization method to use.

Declaration

public BinaryThresholdFilter(BinarizationMethod binarizationMethod)

Parameters

Type	Name	Description
BinarizationMethod	binarizationMethod	Binarization method to use.

BinaryThresholdFilter(Color, Color, Single)

Initializes a new instance of the BinaryThresholdFilter class with the specified upper and lower colors, and threshold.

Declaration

public BinaryThresholdFilter(Color upper, Color lower, float threshold)

Parameters

Type	Name	Description
IronSoftware.Drawing.Color	upper	The color to use for pixels that are above the threshold.
IronSoftware.Drawing.Color	lower	The color to use for pixels that are below the threshold.
System.Single	threshold	Threshold limit (0.0-1.0) to consider for binarization.

BinaryThresholdFilter(Color, Color, Single, BinarizationMethod)

Initializes a new instance of the BinaryThresholdFilter class with the specified upper and lower colors, threshold, and binarization method.

Declaration

public BinaryThresholdFilter(Color upper, Color lower, float threshold, BinarizationMethod binarizationMethod)

Parameters

Type	Name	Description
IronSoftware.Drawing.Color	upper	The color to use for pixels that are above the threshold.
IronSoftware.Drawing.Color	lower	The color to use for pixels that are below the threshold.
System.Single	threshold	Threshold limit (0.0-1.0) to consider for binarization.
BinarizationMethod	binarizationMethod	Binarization method to use.

BinaryThresholdFilter(Color, Color, Single, Rectangle)

Initializes a new instance of the BinaryThresholdFilter class with the specified Upper, Lower, Threshold and Rectangle.

Declaration

public BinaryThresholdFilter(Color upper, Color lower, float threshold, Rectangle rectangle)

Parameters

Type	Name	Description
IronSoftware.Drawing.Color	upper	The color to use for pixels that are above the threshold.
IronSoftware.Drawing.Color	lower	The color to use for pixels that are below the threshold.
System.Single	threshold	Threshold limit (0.0-1.0) to consider for binarization.
IronSoftware.Drawing.Rectangle	rectangle	Rectangle region to apply the filter on.

BinaryThresholdFilter(Color, Color, Single, Rectangle, BinarizationMethod)

Initializes a new instance of the BinaryThresholdFilter class with the specified upper and lower colors, threshold, rectangle, and binarization method.

Declaration

public BinaryThresholdFilter(Color upper, Color lower, float threshold, Rectangle rectangle, BinarizationMethod binarizationMethod)

Parameters

Type	Name	Description
IronSoftware.Drawing.Color	upper	The color to use for pixels that are above the threshold.
IronSoftware.Drawing.Color	lower	The color to use for pixels that are below the threshold.
System.Single	threshold	Threshold limit (0.0-1.0) to consider for binarization.
IronSoftware.Drawing.Rectangle	rectangle	Rectangle region to apply the filter on.
BinarizationMethod	binarizationMethod	Binarization method to use.

BinaryThresholdFilter(Single)

Initializes a new instance of the BinaryThresholdFilter class with the specified threshold.

Declaration

public BinaryThresholdFilter(float threshold)

Parameters

Type	Name	Description
System.Single	threshold	Threshold to apply for binarization. Must be between [0.0-1.0].

BinaryThresholdFilter(Single, BinarizationMethod)

Initializes a new instance of the BinaryThresholdFilter class with the specified threshold and binarization.

Declaration

public BinaryThresholdFilter(float threshold, BinarizationMethod binarizationMethod)

Parameters

Type	Name	Description
System.Single	threshold	Threshold to apply for binarization. Must be between [0.0-1.0].
BinarizationMethod	binarizationMethod	Binarization method to use.

Properties

BinarizationMethod

Binarization method to use. Default = Otsu's Method.

Declaration

public BinarizationMethod BinarizationMethod { get; set; }

Property Value

Type	Description
BinarizationMethod

Lower

The color to use for pixels that are below the threshold.

Declaration

public Color Lower { get; set; }

Property Value

Type	Description
IronSoftware.Drawing.Color

Rectangle

Rectangle region to apply the filter on.

Declaration

public Rectangle Rectangle { get; set; }

Property Value

Type	Description
IronSoftware.Drawing.Rectangle

Threshold

The threshold to apply binarization of the image. Must be between [0.0-1.0]. Default = 0.4. With Otsu's method, this value is not used.

Declaration

public float Threshold { get; set; }

Property Value

Type	Description
System.Single

Upper

The color to use for pixels that are above the threshold.

Declaration

public Color Upper { get; set; }

Property Value

Type	Description
IronSoftware.Drawing.Color

Implements

IImageFilter