如何使颜色在BufferedImage中透明并另存为PNG

如何使颜色在BufferedImage中透明并另存为PNG

我最近这样做是为了回答我的项目经理的问题。
将灰色转换为透明的功能是：

  private Image TransformGrayToTransparency(BufferedImage image)  {    ImageFilter filter = new RGBImageFilter()    {      public final int filterRGB(int x, int y, int rgb)      {        return (rgb << 8) & 0xFF000000;      }    };    ImageProducer ip = new FilteredImageSource(image.getSource(), filter);    return Toolkit.getDefaultToolkit().createImage(ip);  }

实际上，它作用于灰度图像上，因此我只是将RGB分量（R一个）复制到alpha中，而丢弃了其他与我相同的分量。
您可以调整它以过滤特定的颜色，例如。平等或范围等的测试
。当然，数据的BufferedImage必须BufferedImage.TYPE_INT_ARGB类型。

我没有解决保存的问题，因为这很简单，但是我也可以添加此代码页。

[编辑]要将图像转换为BufferedImage：

BufferedImage dest = new BufferedImage(    imageWidth, imageHeight,    BufferedImage.TYPE_INT_ARGB);Graphics2D g2 = dest.createGraphics();g2.drawImage(image, 0, 0, null);g2.dispose();

[编辑2]我是在克里斯托弗发布完整的解决方案之后来到这里的，但是这是我的，我展示了如何使一系列颜色透明。可以改进，例如。而是使用HSB组件。

import java.awt.*;import java.awt.image.BufferedImage;import java.awt.image.FilteredImageSource;import java.awt.image.ImageFilter;import java.awt.image.ImageProducer;import java.awt.image.RGBImageFilter;import java.io.*;import javax.imageio.ImageIO;public class AddTransparency{  AddTransparency() throws IOException  {    String imagePath = "E:/documents/images/";    File inFile = new File(imagePath, "map.png");    BufferedImage image = ImageIO.read(inFile);    Image transpImg1 = TransformGrayToTransparency(image);    BufferedImage resultImage1 = ImageToBufferedImage(transpImg1, image.getWidth(), image.getHeight());    File outFile1 = new File(imagePath, "map_with_transparency1.png");    ImageIO.write(resultImage1, "PNG", outFile1);    Image transpImg2 = TransformColorToTransparency(image, new Color(0, 50, 77), new Color(200, 200, 255));    BufferedImage resultImage2 = ImageToBufferedImage(transpImg2, image.getWidth(), image.getHeight());    File outFile2 = new File(imagePath, "map_with_transparency2.png");    ImageIO.write(resultImage2, "PNG", outFile2);  }  private Image TransformGrayToTransparency(BufferedImage image)  {    ImageFilter filter = new RGBImageFilter()    {      public final int filterRGB(int x, int y, int rgb)      {        return (rgb << 8) & 0xFF000000;      }    };    ImageProducer ip = new FilteredImageSource(image.getSource(), filter);      return Toolkit.getDefaultToolkit().createImage(ip);  }  private Image TransformColorToTransparency(BufferedImage image, Color c1, Color c2)  {    // Primitive test, just an example    final int r1 = c1.getRed();    final int g1 = c1.getGreen();    final int b1 = c1.getBlue();    final int r2 = c2.getRed();    final int g2 = c2.getGreen();    final int b2 = c2.getBlue();    ImageFilter filter = new RGBImageFilter()    {      public final int filterRGB(int x, int y, int rgb)      {        int r = (rgb & 0xFF0000) >> 16;        int g = (rgb & 0xFF00) >> 8;        int b = rgb & 0xFF;        if (r >= r1 && r <= r2 && g >= g1 && g <= g2 && b >= b1 && b <= b2)        {          // Set fully transparent but keep color          return rgb & 0xFFFFFF;        }        return rgb;      }    };    ImageProducer ip = new FilteredImageSource(image.getSource(), filter);      return Toolkit.getDefaultToolkit().createImage(ip);  }  private BufferedImage ImageToBufferedImage(Image image, int width, int height)  {    BufferedImage dest = new BufferedImage(        width, height, BufferedImage.TYPE_INT_ARGB);    Graphics2D g2 = dest.createGraphics();    g2.drawImage(image, 0, 0, null);    g2.dispose();    return dest;  }  public static void main(String[] args) throws IOException  {    AddTransparency at = new AddTransparency();  }}