Contrast Property (Device)

In This Topic

Gets or sets the contrast of gray/palette/color images for current scan session.

Syntax

'Declaration

Public Property Contrast As Single

public float Contrast { get; set; }

public: __property float get_Contrast();
public: __property void set_Contrast(
   float value
);

public:
property float Contrast {
   float get();
   void set(float value);
}

Exceptions

Exception	Description
TwainInvalidStateException	Thrown if device is in wrong state.
TwainDeviceCapabilityException	Thrown if device does not support capability.
DebuggerException	Thrown if the .NET debugger is used and the function evaluation requires all threads to run.

Remarks

Call this property only when device is opened (State == DeviceState.Opened).

Supported values of brightness can be received by the GetSupportedContrastValues method.

This property has effect only for gray/palette/color images. Threshold property must be used for black-white images.

Example

This C#/VB.NET code shows how to adjust brightness/contrast and acquire color images from the device.

VB.NET


Public Sub ScanColorImageWithBrightness(device As Vintasoft.Twain.Device)
    device.ShowUI = False
    device.DisableAfterAcquire = True

    device.Open()
    device.PixelType = Vintasoft.Twain.PixelType.RGB
    device.UnitOfMeasure = Vintasoft.Twain.UnitOfMeasure.Inches
    device.Resolution = New Vintasoft.Twain.Resolution(300.0F, 300.0F)
    device.Brightness = 128.0F
    device.Contrast = 0

    device.Acquire()
End Sub


public void ScanColorImageWithBrightness(Vintasoft.Twain.Device device)
{
    device.ShowUI = false;
    device.DisableAfterAcquire = true;

    device.Open();
    device.PixelType = Vintasoft.Twain.PixelType.RGB;
    device.UnitOfMeasure = Vintasoft.Twain.UnitOfMeasure.Inches;
    device.Resolution = new Vintasoft.Twain.Resolution(300f, 300f);
    device.Brightness = 128f;
    device.Contrast = 0;

    device.Acquire();
}

Requirements

Target Platforms: .NET 10; .NET 9; .NET 8; .NET 7; .NET 6; .NET Framework 4.8, 4.7, 4.6, 4.5, 4.0, 3.5

Reference

Device Class
Device Members

GetSupportedContrastValues
Open
Threshold

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