如何将图像转换为java中的透明图像

Question

如何将图像的白色背景转换为透明背景？任何人都可以告诉我如何做到这一点？

Answer 1

从谷歌的第一个结果是这样的：

进行彩色透明 http://www.rgagnon.com/javadetails/java-0265.html

它使透明图像的蓝色部分，但我敢肯定，你可以适应，要使用白intstead

（提示：通过Color.WHITE到makeColorTransparent功能，而不是Color.BLUE）

发现了一个比较完整的现代ANSW呃在这里：How to make a color transparent in a BufferedImage and save as PNG

Answer 2

这是我的解决方案。只要背景图像颜色位于左上角，该过滤器就会从任何图像中移除背景。

private static class BackgroundFilter extends RGBImageFilter{ 

    boolean setUp = false; 
    int bgColor; 

    @Override 
    public int filterRGB(int x, int y, int rgb) { 
     int colorWOAlpha = rgb & 0xFFFFFF; 
     if(! setUp && x == 0 && y == 0){ 
      bgColor = colorWOAlpha; 
      setUp = true; 
     } 
     else if(colorWOAlpha == bgColor) 
      return colorWOAlpha; 
     return rgb; 
    } 
} 

别处......

ImageFilter bgFilter = new BackgroundFilter(); 
ImageProducer ip = new FilteredImageSource(image.getSource(), bgFilter); 
image = Toolkit.getDefaultToolkit().createImage(ip); 

Answer 3

这种方法会使背景透明。您需要传递想要修改的图像，颜色和容差。

final int color = ret.getRGB(0, 0); 
final Image imageWithTransparency = makeColorTransparent(ret, new Color(color), 10); 
final BufferedImage transparentImage = imageToBufferedImage(imageWithTransparency); 

private static BufferedImage imageToBufferedImage(final Image image) { 
     final BufferedImage bufferedImage = 
      new BufferedImage(image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_ARGB); 
     final Graphics2D g2 = bufferedImage.createGraphics(); 
     g2.drawImage(image, 0, 0, null); 
     g2.dispose(); 
     return bufferedImage; 
} 


private static Image makeColorTransparent(final BufferedImage im, final Color color, int tolerance) { 
    int temp = 0; 

    if (tolerance < 0 || tolerance > 100) { 

     System.err.println("The tolerance is a percentage, so the value has to be between 0 and 100."); 

     temp = 0; 

    } else { 

     temp = tolerance * (0xFF000000 | 0xFF000000)/100; 

    } 

    final int toleranceRGB = Math.abs(temp); 



    final ImageFilter filter = new RGBImageFilter() { 

     // The color we are looking for (white)... Alpha bits are set to opaque 

     public int markerRGBFrom = (color.getRGB() | 0xFF000000) - toleranceRGB; 

     public int markerRGBTo = (color.getRGB() | 0xFF000000) + toleranceRGB; 



     public final int filterRGB(final int x, final int y, final int rgb) { 

      if ((rgb | 0xFF000000) >= markerRGBFrom && (rgb | 0xFF000000) <= markerRGBTo) { 

       // Mark the alpha bits as zero - transparent 

       return 0x00FFFFFF & rgb; 

      } else { 

       // Nothing to do 

       return rgb; 

      } 

     } 

    }; 

    final ImageProducer ip = new FilteredImageSource(im.getSource(), filter); 

    return Toolkit.getDefaultToolkit().createImage(ip); 
}