Class ContrastFilter

A filter to adjust image contrast.

Inheritance
System.Object
ContrastFilter
Implements
Namespace: IronBarCode
Assembly: IronBarCode.dll
Syntax
public class ContrastFilter : Object, IImageFilter

ContrastFilter widens the difference in intensity between the light and dark regions of a barcode image, the correction for a washed-out or flat photo where the bars and the background sit too close in tone for a reliable read. Pushing the contrast up makes the black bars darker and the white spaces lighter, sharpening the boundary a decoder keys on; pulling it down has the opposite, softening effect. It is one of the most frequently applied passes, often paired with a sharpen step.

The filter implements IImageFilter and is added to the ImageFilterCollection on BarcodeReaderOptions.ImageFilters, run in collection order before decoding. A developer constructs it, adds it to the collection, and passes the options to BarcodeReader.Read. The single Amount property controls the strength: the default value of 1 leaves the image unchanged, 0 produces a fully gray image, and values above 1 increase contrast. The single-argument constructor sets Amount at creation.

using IronBarCode;

var options = new BarcodeReaderOptions
{
    ImageFilters = new ImageFilterCollection { new ContrastFilter(2.0f) }
};
var results = BarcodeReader.Read("washed-out.png", options);

The image correction how-to demonstrates the contrast pass on a sample, and the imperfect barcode example reads a degraded barcode after correction.

Constructors

ContrastFilter()

Initializes a new instance of the ContrastFilter class.

Declaration
public ContrastFilter()

ContrastFilter(Single)

Initializes a new instance of the ContrastFilter class with the specified amount.

Declaration
public ContrastFilter(float amount)
Parameters
Type Name Description
System.Single amount

The proportion of the conversion. Value must be between [0, 10].

Properties

Amount

The proportion of the conversion. Value must be between [0, 10]. Default = 1.0.

Declaration
public float Amount { get; set; }
Property Value
Type Description
System.Single

Implements