CreateAlphaImage Method

Summary

Creates a grayscale image from this RasterImage alpha channel data.

Syntax

Objective-C

C++

Java

public RasterImage CreateAlphaImage()

Public Function CreateAlphaImage() As RasterImage

- (nullable LTRasterImage *)createAlphaImage:(NSError **)error

public RasterImage createAlphaImage()

public: 
RasterImage^ CreateAlphaImage();

Return Value

The newly create image, which contains the source image alpha channel data.

Remarks

Only 16-bit, 32-bit, and 64-bit images can have an alpha channel. If the source image has another color resolution, the result is an image filled with zeros.

Typically, the alpha channel contains a mask that is used for transparency.

For more information, refer to Implementing Transparency.

For more information, refer to Grayscale Images.

For more information, refer to Saving A Region.

Example

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Core; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Dicom; 
using Leadtools.Drawing; 
using Leadtools.Controls; 
using LeadtoolsExamples.Common; 
using Leadtools.Svg; 
 
public void CreateAlphaImageExample() 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
   // Load the image, at 16 bit per pixel. 
   RasterImage image = codecs.Load(Path.Combine(ImagesPath.Path, "IMAGE1.CMP"), 16, CodecsLoadByteOrder.Bgr, 1, 1); 
 
   // Specify a rectangle to define the region. 
   LeadRect ellipseRectangle = new LeadRect(image.Width / 8, image.Height / 8, image.Width / 2, image.Height / 2); 
 
   // Create an elliptical region in the AlphaImage. 
   image.AddEllipseToRegion(null, ellipseRectangle, RasterRegionCombineMode.Set); 
 
   // Create a mask image from the region. 
   RasterImage alphaImage = image.CreateMaskFromRegion(); 
 
   // Update the alpha channel in the main image. 
   image.SetAlphaImage(alphaImage); 
 
   // Save the image at 16 bits per pixel to keep the alpha channel. 
   codecs.Save(image, Path.Combine(ImagesPath.Path, "TestAlpha.TIF"), RasterImageFormat.Tif, 24, 1, 1, 1, CodecsSavePageMode.Overwrite); 
 
   // Load the bitmap that we just saved and get its alpha channel. 
   image = codecs.Load(Path.Combine(ImagesPath.Path, "TestAlpha.TIF"), 16, CodecsLoadByteOrder.Bgr, 1, 1); 
 
   alphaImage = image.CreateAlphaImage(); 
 
   // Use the AlphaBitmap as a mask to set the region in the MainBitmap. 
   image.AddMaskToRegion(null, alphaImage, RasterRegionCombineMode.Set); 
 
   image.Dispose(); 
   codecs.Dispose(); 
}

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Core 
Imports Leadtools.ImageProcessing.Color 
Imports Leadtools.Controls 
Imports Leadtools.Dicom 
Imports Leadtools.Drawing 
Imports Leadtools.Svg 
 
Public Sub CreateAlphaImageExample() 
   Dim codecs As RasterCodecs = New RasterCodecs() 
   ' Load the image, at 16 bit per pixel. 
   Dim image As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1.CMP"), 16, CodecsLoadByteOrder.Bgr, 1, 1) 
 
   ' Specify a rectangle to define the region. 
   Dim EllipseRectangle As LeadRect = New LeadRect(image.Width \ 8, image.Height \ 8, image.Width \ 2, image.Height \ 2) 
 
   ' Create an elliptical region in the AlphaImage. 
   image.AddEllipseToRegion(Nothing, EllipseRectangle, RasterRegionCombineMode.Set) 
 
   ' Create a mask image from the region. 
   Dim alphaImage As RasterImage = image.CreateMaskFromRegion() 
 
   ' Update the alpha channel in the main image. 
   image.SetAlphaImage(alphaImage) 
 
   ' Save the image at 16 bits per pixel to keep the alpha channel. 
   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "TestAlpha.TIF"), RasterImageFormat.Tif, 24, 1, 1, 1, CodecsSavePageMode.Overwrite) 
 
   ' Load the bitmap that we just saved and get its alpha channel. 
   image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "TestAlpha.TIF"), 16, CodecsLoadByteOrder.Bgr, 1, 1) 
 
   alphaImage = image.CreateAlphaImage() 
 
   ' Use the AlphaBitmap as a mask to set the region in the MainBitmap. 
   image.AddMaskToRegion(Nothing, alphaImage, RasterRegionCombineMode.Set) 
 
   image.Dispose() 
   codecs.Dispose() 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class

c#[Silverlight C# Example] 
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Dicom; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Core; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Examples; 
using Leadtools.Windows.Media; 
 
public void CreateAlphaImageExample(RasterImage image, Stream destStream) 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
 
   // Specify a rectangle to define the region. 
   LeadRect EllipseRectangle = new LeadRect(image.Width / 8, image.Height / 8, image.Width / 2, image.Height / 2); 
 
   // Create a region in the AlphaImage. 
   image.AddRectangleToRegion(null, EllipseRectangle, RasterRegionCombineMode.Set); 
 
   // Create a mask image from the region. 
   RasterImage alphaImage = image.CreateMaskFromRegion(); 
 
   // Update the alpha channel in the main image. 
   image.SetAlphaImage(alphaImage); 
 
   // Save the image at 16 bits per pixel to keep the alpha channel. 
   codecs.Save(image, destStream, RasterImageFormat.Tif, 24, 1, 1, 1, CodecsSavePageMode.Overwrite); 
 
   // Load the bitmap that we just saved and get its alpha channel. 
   image = codecs.Load(destStream, 16, CodecsLoadByteOrder.Bgr, 1, 1); 
 
   alphaImage = image.CreateAlphaImage(); 
 
   // Use the AlphaBitmap as a mask to set the region in the MainBitmap. 
   image.AddMaskToRegion(null, alphaImage, RasterRegionCombineMode.Set); 
 
   image.Dispose(); 
} 
vb[Silverlight VB Example] 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Dicom 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Core 
Imports Leadtools.ImageProcessing.Color 
Imports Leadtools.Windows.Media 
 
Public Sub CreateAlphaImageExample(ByVal image As RasterImage, ByVal destStream As Stream) 
   Dim codecs As RasterCodecs = New RasterCodecs() 
 
   ' Specify a rectangle to define the region. 
   Dim EllipseRectangle As LeadRect = New LeadRect(image.Width / 8, image.Height / 8, image.Width / 2, image.Height / 2) 
 
   ' Create a region in the AlphaImage. 
   image.AddRectangleToRegion(Nothing, EllipseRectangle, RasterRegionCombineMode.Set) 
 
   ' Create a mask image from the region. 
   Dim alphaImage As RasterImage = image.CreateMaskFromRegion() 
 
   ' Update the alpha channel in the main image. 
   image.SetAlphaImage(alphaImage) 
 
   ' Save the image at 16 bits per pixel to keep the alpha channel. 
   codecs.Save(image, destStream, RasterImageFormat.Tif, 24, 1, 1, 1, CodecsSavePageMode.Overwrite) 
 
   ' Load the bitmap that we just saved and get its alpha channel. 
   image = codecs.Load(destStream, 16, CodecsLoadByteOrder.Bgr, 1, 1) 
 
   alphaImage = image.CreateAlphaImage() 
 
   ' Use the AlphaBitmap as a mask to set the region in the MainBitmap. 
   image.AddMaskToRegion(Nothing, alphaImage, RasterRegionCombineMode.Set) 
 
   image.Dispose() 
End Sub

Requirements

Target Platforms

Reference

RasterImage Class

RasterImage Members

Download our FREE evaluation

Help Version 20.0.2020.4.2

Leadtools Assembly

Introduction

Getting Started

Namespaces

Leadtools Namespace

Leadtools.ImageProcessing Namespace

Assemblies