Question

like this
gif image

it has transparent background,

when i using ImageIO.write(image,"jpg", file) to save,it’s be broken

the broken result is here

how to fix it problem? thank you

my code:

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import junit.framework.TestCase;

public class ImageResize1  extends TestCase{

    public void testT1() throws IOException{
        URL url=new URL("http://ec.europa.eu/culture/media/programme/images/logos/01_tr_media_col/01_tr_media_col_gif.gif");
        BufferedImage image=ImageIO.read(url);
        File file=new File("C:/temp/java/t7.jpg");
        ImageIO.write(image,"jpg", file);
    }
}

i used:

for(int x = 0; x < scaled.getWidth(); x++) {
    for(int y = 0; y < scaled.getHeight(); y++) {
        int rgb = scaled.getRGB(x, y);
        int alpha = (rgb >> 24) & 0xff;
        if(alpha != 255) {
            scaled.setRGB(x, y,-1); //set white
        }
    }
}

check it from here

it’s not right,result is here

Answer 1

AreaAveragingScaleFilter scaleFilter =
    new AreaAveragingScaleFilter(
                Math.round(originalWidth / factorX),
                Math.round(originalHeight / factorY));
ImageProducer producer = new FilteredImageSource(original.getSource(), scaleFilter);
ImageGenerator generator = new ImageGenerator();
producer.startProduction(generator);
BufferedImage scaled = generator.getImage();

for(int x = 0; x < scaled.getWidth(); x++) {
    for(int y = 0; y < scaled.getHeight(); y++) {
        int rgb = scaled.getRGB(x, y);
        int alpha = (rgb >> 24) & 0xff;
        if(alpha != 255) {
            scaled.setRGB(x, y,-1); //set white
        }
    }
}


JPEGImageWriteParam param = new JPEGImageWriteParam(null);
param.setCompressionMode(JPEGImageWriteParam.MODE_EXPLICIT);
param.setCompressionQuality((float) 0.85);
java.util.Iterator<ImageWriter> it = ImageIO.getImageWritersBySuffix("jpg");
ImageWriter writer = it.next();
dest.getParentFile().mkdirs();
writer.setOutput(new FileImageOutputStream(dest));
writer.write(null, new IIOImage(scaled, null, null), param);
writer.dispose();   

Check it from here