缓冲图像调整大小

Question

我正在尝试调整缓冲图像的大小。我能够存储它并显示在 jframe 上没有问题，但我似乎无法调整它的大小。关于如何更改它以使其工作并将图像显示为 200*200 文件的任何提示都会很棒

private void profPic(){
    String path = factory.getString("bottle");
    BufferedImage img = ImageIO.read(new File(path));
}


public static BufferedImage resize(BufferedImage img, int newW, int newH) {  
    int w = img.getWidth();  
    int h = img.getHeight();  
    BufferedImage dimg = new BufferedImage(newW, newH, img.getType());  
    Graphics2D g = dimg.createGraphics();  
    g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
    RenderingHints.VALUE_INTERPOLATION_BILINEAR);  
    g.drawImage(img, 0, 0, newW, newH, 0, 0, w, h, null);  
    g.dispose();  
    return dimg;  
}  

Answer 1

更新答案

我不记得为什么my original answer 有效，但在单独的环境中对其进行了测试，我同意，原来接受的答案不起作用（为什么我说它有效，我也不记得了）。另一方面，这确实有效：

public static BufferedImage resize(BufferedImage img, int newW, int newH) { 
    Image tmp = img.getScaledInstance(newW, newH, Image.SCALE_SMOOTH);
    BufferedImage dimg = new BufferedImage(newW, newH, BufferedImage.TYPE_INT_ARGB);

    Graphics2D g2d = dimg.createGraphics();
    g2d.drawImage(tmp, 0, 0, null);
    g2d.dispose();

    return dimg;
}  

Answer 2

如果只需要在resize 方法中调整BufferedImage 的大小，那么Thumbnailator 库可以很容易地做到这一点：

public static BufferedImage resize(BufferedImage img, int newW, int newH) {
  return Thumbnails.of(img).size(newW, newH).asBufferedImage();
}

以上代码将调整img 的大小以适应newW 和newH 的尺寸，同时保持原始图像的纵横比。

如果不需要保持纵横比并且需要精确调整到给定尺寸，则可以使用forceSize 方法代替size 方法：

public static BufferedImage resize(BufferedImage img, int newW, int newH) {
  return Thumbnails.of(img).forceSize(newW, newH).asBufferedImage();
}

---

使用Image.getScaledInstance方法并不能保证调整后的图像会保持原始图像的纵横比，而且通常速度很慢。

Thumbnailator 使用一种技术来逐步调整图像的大小，可以是several times faster than Image.getScaledInstance，同时实现通常可比较的图像质量。

免责声明：我是这个库的维护者。

Answer 3

这是我用来调整缓冲图像大小的一些代码，没有多余的装饰，非常快：

public static BufferedImage scale(BufferedImage src, int w, int h)
{
    BufferedImage img = 
            new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
    int x, y;
    int ww = src.getWidth();
    int hh = src.getHeight();
    int[] ys = new int[h];
    for (y = 0; y < h; y++)
        ys[y] = y * hh / h;
    for (x = 0; x < w; x++) {
        int newX = x * ww / w;
        for (y = 0; y < h; y++) {
            int col = src.getRGB(newX, ys[y]);
            img.setRGB(x, y, col);
        }
    }
    return img;
}

Answer 4

此类从文件中调整大小并获取格式名称：

import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageInputStream;
import org.apache.commons.io.IOUtils;

public class ImageResizer {

public static void main(String as[]) throws IOException{

    File f = new File("C:/Users/samsungrob/Desktop/shuttle.jpg");

    byte[] ba = resize(f, 600, 600);

    IOUtils.write(ba, new FileOutputStream( new File("C:/Users/samsungrob/Desktop/shuttle_resized.jpg") ) );

}




public static byte[] resize(File file,
                            int maxWidth, int maxHeight) throws IOException{
    int scaledWidth = 0, scaledHeight = 0;

    BufferedImage img = ImageIO.read((ImageInputStream) file );

    scaledWidth = maxWidth;
    scaledHeight = (int) (img.getHeight() * ( (double) scaledWidth / img.getWidth() ));

    if (scaledHeight> maxHeight) {
        scaledHeight = maxHeight;
        scaledWidth= (int) (img.getWidth() * ( (double) scaledHeight/ img.getHeight() ));

        if (scaledWidth > maxWidth) {
            scaledWidth = maxWidth;
            scaledHeight = maxHeight;
        }
    }

    Image resized =  img.getScaledInstance( scaledWidth, scaledHeight, Image.SCALE_SMOOTH);

    BufferedImage buffered = new BufferedImage(scaledWidth, scaledHeight, Image.SCALE_REPLICATE);

    buffered.getGraphics().drawImage(resized, 0, 0 , null);

    String formatName = getFormatName( file ) ;

    ByteArrayOutputStream out = new ByteArrayOutputStream();

    ImageIO.write(buffered,
            formatName,
            out);

    return out.toByteArray();
}


private static String getFormatName(ImageInputStream iis) {
    try { 

        // Find all image readers that recognize the image format
        Iterator iter = ImageIO.getImageReaders(iis);
        if (!iter.hasNext()) {
            // No readers found
            return null;
        }

        // Use the first reader
        ImageReader reader = (ImageReader)iter.next();

        // Close stream
        iis.close();

        // Return the format name
        return reader.getFormatName();
    } catch (IOException e) {
    }

    return null;
}

private static String getFormatName(File file) throws IOException {
    return getFormatName( ImageIO.createImageInputStream(file) );
}

private static String getFormatName(InputStream is) throws IOException {
    return getFormatName( ImageIO.createImageInputStream(is) );
}

}

Answer 5

如果您只想使用“平衡”平滑，这是 imgscalr 中实际情况的简化版本：

/**
 * Takes a BufferedImage and resizes it according to the provided targetSize
 *
 * @param src the source BufferedImage
 * @param targetSize maximum height (if portrait) or width (if landscape)
 * @return a resized version of the provided BufferedImage
 */
private BufferedImage resize(BufferedImage src, int targetSize) {
    if (targetSize <= 0) {
        return src; //this can't be resized
    }
    int targetWidth = targetSize;
    int targetHeight = targetSize;
    float ratio = ((float) src.getHeight() / (float) src.getWidth());
    if (ratio <= 1) { //square or landscape-oriented image
        targetHeight = (int) Math.ceil((float) targetWidth * ratio);
    } else { //portrait image
        targetWidth = Math.round((float) targetHeight / ratio);
    }
    BufferedImage bi = new BufferedImage(targetWidth, targetHeight, src.getTransparency() == Transparency.OPAQUE ? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB);
    Graphics2D g2d = bi.createGraphics();
    g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR); //produces a balanced resizing (fast and decent quality)
    g2d.drawImage(src, 0, 0, targetWidth, targetHeight, null);
    g2d.dispose();
    return bi;
}

Answer 6

试试 imgscalr 库。我发现的最好的库——速度非常快、质量好且易于使用

BufferedImage thumbnail = Scalr.resize(image, 150);

已弃用的链接：http://www.thebuzzmedia.com/software/imgscalr-java-image-scaling-library/

Apache 2 许可证

Answer 7

看看这个，有帮助：

BufferedImage bImage = ImageIO.read(new File(C:\image.jpg);

BufferedImage thumbnail = Scalr.resize(bImage,  Scalr.Method.SPEED, Scalr.Mode.FIT_TO_WIDTH,
                                       750, 150, Scalr.OP_ANTIALIAS);