如何在BufferedImage中使颜色透明并另存为PNG

我一直在网上搜索此信息,但没有找到任何体面的帮助。

我有一个BufferedImage,已与ImageIO一起阅读。现在,我想使该图像中的某种颜色变为透明,然后将图像另存为PNG。

我知道出于明显的原因我不能仅仅“绘制”透明颜色,所以我猜我需要某种过滤器。

有人为此提供了一些示例代码吗?

回答:

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。

你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,因为它很琐碎,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Christoffer发布他的完整解决方案之后来的,但这是我的,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();

}

}

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