Visual Basic (Declaration) | |
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Public Function CreateAlphaImage() As RasterImage |
Visual Basic (Usage) | Copy Code |
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Dim instance As RasterImage Dim value As RasterImage value = instance.CreateAlphaImage() |
C# | |
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public RasterImage CreateAlphaImage() |
C++/CLI | |
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public: RasterImage^ CreateAlphaImage(); |
Return Value
The newly create image, which contains the source image alpha channel data.
Visual Basic | Copy Code |
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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# | Copy Code |
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public void CreateAlphaImageExample() { RasterCodecs codecs = new RasterCodecs(); // Load the image, at 16 bit per pixel. RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "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(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(null, alphaImage, RasterRegionCombineMode.Set); image.Dispose(); codecs.Dispose(); } static class LEAD_VARS { public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; } |
SilverlightCSharp | Copy Code |
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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(); } |
SilverlightVB | Copy Code |
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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 |
Only 16-, 32-, 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.
Target Platforms: Silverlight, Windows XP, Windows Server 2003 family, Windows Server 2008 family, Windows Vista, Windows 7, MAC OS/X (Intel Only), Windows Phone 7