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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