Question

不确定我做错了什么，但保存的图像与原来的~500px高相同。我试图将图像设置为100px高并保持aspectratio相同。然后保存较小的版本。

BufferedImage original = ImageIO.read(inputStream);
Integer width = original.getWidth();
float aspectratio = (float)original.getWidth()/(float)original.getHeight();
Integer newwidth= Math.round(100*aspectratio);
BufferedImage scaledImage = new BufferedImage(newwidth,100,original.getType());
Graphics2D g = scaledImage.createGraphics();
g.drawImage(scaledImage,0,0,null);
g.dispose();
ImageIO.write(scaledImage, "PNG", result);

Answer 1

问题是drawImage(Image, int, int, ImageObserver)无法缩放图像。此外，您正在将图像绘制到自身。您需要使用缩放图像的drawImage重载，如下所示：

// ...
Graphics2D g = scaledImage.createGraphics();
g.drawImage(original, 0, 0, scaledImage.getWidth(), scaledImage.getHeight(), 0, 0, original.getWidth(), original.getHeight(), null);
// ...

查看JavaDocs for Graphics上的更多信息。

Answer 2

小例子，取决于你的代码

import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;


public class ImageScaler {


    public static void main(String[] args) {
        try {
            // Load the original image
            BufferedImage image = ImageIO.read(new File(("PATH_TO_YOUR_ORIGINAL_IMAGE")));
            float wh = (float)image.getWidth()/(float)image.getHeight();
            int aspect = Math.round(100*wh);
            // get a scaledInstance from the original image depending on your
            // calculated aspectRation
            Image scaledInstance = image.getScaledInstance(aspect, 100, Image.SCALE_SMOOTH);
            // convert the Image to BufferedImage
            BufferedImage bi = getScaledBufferedImage(scaledInstance);
            // Write it out
            File outputFile = new File("PATH_TO_SAVE_THE_SCALED_VERSION");
            ImageIO.write(bi, "png", outputFile);
        } catch (IOException ex) {
            Logger.getLogger(ImageScaler.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    /**
     * Converts a given Image instance to a BufferedImage
     * @param image
     * @return BufferedImage
     */
    private static BufferedImage getScaledBufferedImage(final Image image) {

        // check if image is instanceof BufferedImages
        if(image instanceof BufferedImage) {
            return (BufferedImage)image;
        }

        // create a new BufferedImage
        BufferedImage bi = new BufferedImage(image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_ARGB);

        // get the Graphics Object from the BufferedImage
        Graphics g = bi.getGraphics();
        // draw the Image to the BufferedImage
        g.drawImage(image, 0, 0, null);
        // dispose the Graphics
        g.dispose();

        return bi;
    }

}

帕特里克

Java Image不缩放

2 个答案: