CreateAlphaImage Method

Summary

Creates a grayscale image from this RasterImage alpha channel data.

Syntax

Objective-C

C++/CLI

Java

Python

public RasterImage CreateAlphaImage()

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

public RasterImage createAlphaImage();

public: 
RasterImage^ CreateAlphaImage();

def CreateAlphaImage(self):

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

Java

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 Leadtools.Svg; 
 
 
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:\LEADTOOLS23\Resources\Images"; 
}

 
import java.io.File; 
import java.io.FileInputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.util.ArrayList; 
import java.util.List; 
 
import org.junit.*; 
import org.junit.runner.JUnitCore; 
import org.junit.runner.Result; 
import org.junit.runner.notification.Failure; 
import static org.junit.Assert.*; 
 
import leadtools.*; 
import leadtools.codecs.*; 
import leadtools.imageprocessing.core.*; 
import leadtools.svg.*; 
import leadtools.imageprocessing.CloneCommand; 
import leadtools.imageprocessing.FillCommand; 
import leadtools.imageprocessing.FlipCommand; 
import leadtools.imageprocessing.GrayscaleCommand; 
import leadtools.imageprocessing.color.InvertCommand; 
import leadtools.imageprocessing.color.PosterizeCommand; 
 
 
public void createAlphaImageExample() { 
   final String LEAD_VARS_IMAGES_DIR = "C:\\LEADTOOLS23\\Resources\\Images"; 
   RasterCodecs codecs = new RasterCodecs(); 
 
   // Load the image, at 16 bit per pixel. 
   RasterImage image = codecs.load(combine(LEAD_VARS_IMAGES_DIR, "IMAGE1.CMP"), 16, CodecsLoadByteOrder.BGR, 1, 1); 
   String destFileName = combine(LEAD_VARS_IMAGES_DIR, "TestAlpha.TIF"); 
 
   // Specify a rectangle to define the region. 
   LeadRect ellipseRectangle = new LeadRect(image.getWidth() / 8, image.getHeight() / 8, image.getWidth() / 2, 
         image.getHeight() / 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, destFileName, RasterImageFormat.TIF, 24, 1, 1, 1, CodecsSavePageMode.OVERWRITE); 
 
   // Load the bitmap that we just saved and get its alpha channel. 
   image = codecs.load(destFileName, 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); 
 
   // Clean up 
   image.dispose(); 
   codecs.dispose(); 
 
   assertTrue("file unsuccessfully saved to " + destFileName, (new File(destFileName)).exists()); 
   System.out.printf("File saved successfully to %s%n", destFileName); 
}

Requirements

Target Platforms

Reference

RasterImage Class

RasterImage Members

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Help Version 23.0.2024.5.22

Leadtools Assembly

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Leadtools Namespace

Leadtools.ImageProcessing Namespace

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