你好我有一个二维码图像，我想调整大小，当我尝试使用这个代码将其调整为一个小图像时，我总是得到一个blury图像，当我扫描时，二维码不再有效它，但当我使用相同的代码调整大尺寸图像时，它工作正常：
public BufferedImage getScaledInstance(BufferedImage img,
int targetWidth,
int targetHeight,
Object hint,
boolean higherQuality)
{
int type = (img.getTransparency() == Transparency.OPAQUE) ?
BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;
BufferedImage ret = (BufferedImage)img;
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = img.getWidth();
h = img.getHeight();
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = targetWidth;
h = targetHeight;
}
do {
if (higherQuality && w > targetWidth) {
w /= 2;
if (w < targetWidth) {
w = targetWidth;
}
}
if (higherQuality && h > targetHeight) {
h /= 2;
if (h < targetHeight) {
h = targetHeight;
}
}
BufferedImage tmp = new BufferedImage(w, h, type);
Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
// g2.setRenderingHint(RenderingHints.KEY_DITHERING, hint);
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
} while (w != targetWidth || h != targetHeight);
return ret;
}
有什么问题，我不太明白，请至少给我一个提示，谢谢
答案 0 :(得分：26)
我使用仿射变换来完成这个任务，这是我的代码，希望它有所帮助
/**
* scale image
*
* @param sbi image to scale
* @param imageType type of image
* @param dWidth width of destination image
* @param dHeight height of destination image
* @param fWidth x-factor for transformation / scaling
* @param fHeight y-factor for transformation / scaling
* @return scaled image
*/
public static BufferedImage scale(BufferedImage sbi, int imageType, int dWidth, int dHeight, double fWidth, double fHeight) {
BufferedImage dbi = null;
if(sbi != null) {
dbi = new BufferedImage(dWidth, dHeight, imageType);
Graphics2D g = dbi.createGraphics();
AffineTransform at = AffineTransform.getScaleInstance(fWidth, fHeight);
g.drawRenderedImage(sbi, at);
}
return dbi;
}
答案 1 :(得分：8)
根据@ A4L的回答：
更直接的版本。他的解决方案也只是缩放画布而不是图像本身。
public static BufferedImage scale(BufferedImage imageToScale, int dWidth, int dHeight) {
BufferedImage scaledImage = null;
if (imageToScale != null) {
scaledImage = new BufferedImage(dWidth, dHeight, imageToScale.getType());
Graphics2D graphics2D = scaledImage.createGraphics();
graphics2D.drawImage(imageToScale, 0, 0, dWidth, dHeight, null);
graphics2D.dispose();
}
return scaledImage;
}
提高您可以添加的质量
graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
graphics2D.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
答案 2 :(得分：7)
我写了这个我个人也使用过的课程。我希望代码是直截了当的。
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.awt.image.CropImageFilter;
import java.awt.image.FilteredImageSource;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
public class ImageScaler {
private ImageIcon originalImage;
private ImageIcon scaledImage;
public ImageScaler(Image image) {
this.originalImage = new ImageIcon(image);
}
public ImageScaler(String fileName) {
originalImage = new ImageIcon(fileName);
}
public void createScaledImage(int size, ScalingDirection scalingDirection) {
if (scalingDirection == ScalingDirection.HORIZONTAL) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(size, -1, Image.SCALE_SMOOTH));
} else {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(-1, size, Image.SCALE_SMOOTH));
}
}
public void createScaledImage(int size, ScalingDirection scalingDirection, int scale) {
if (scalingDirection == ScalingDirection.HORIZONTAL) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(size, -1, scale));
} else {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(-1, size, scale));
}
}
public void createScaledImage(int width, int height, ScaleType scaleType) {
int imageWidth = originalImage.getImage().getWidth(null);
int imageHeight = originalImage.getImage().getHeight(null);
double originalImageRatio = imageWidth / (double) imageHeight;
double scaledImageRatio = width / (double) height;
if(scaleType == ScaleType.FIT) {
if(imageHeight - (Math.abs(imageWidth - width) / originalImageRatio) <= height) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(width, -1, Image.SCALE_SMOOTH));
} else if(imageWidth - (Math.abs(imageHeight - height) * originalImageRatio) <= width) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(-1, height, Image.SCALE_SMOOTH));
}
} else if(scaleType == ScaleType.FILL) {
if(imageHeight - (Math.abs(imageWidth - width) / originalImageRatio) >= height) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(width, -1, Image.SCALE_SMOOTH));
int thumbHeight = scaledImage.getImage().getHeight(null);
// Crop the image
scaledImage = new ImageIcon(Toolkit.getDefaultToolkit().createImage(new FilteredImageSource(scaledImage.getImage().getSource(), new CropImageFilter(0, (thumbHeight-height)/2, width, height))));
} else if(imageWidth - (Math.abs(imageHeight - height) * originalImageRatio) >= width) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(-1, height, Image.SCALE_SMOOTH));
int thumbWidth = scaledImage.getImage().getWidth(null);
// Crop the image
scaledImage = new ImageIcon(Toolkit.getDefaultToolkit().createImage(new FilteredImageSource(scaledImage.getImage().getSource(), new CropImageFilter((thumbWidth-width)/2, 0, width, height))));
}
}
}
public void saveScaledImage(File file, ImageType imageType) {
if (scaledImage != null) {
BufferedImage bi = new BufferedImage(scaledImage.getIconWidth(), scaledImage.getIconHeight(), BufferedImage.TYPE_INT_RGB);
Graphics g = bi.getGraphics();
g.drawImage(scaledImage.getImage(), 0, 0, null);
try {
ImageIO.write(bi, imageType.value(), file);
} catch (IOException ioe) {
System.out.println("Error occured saving scaled image");
}
} else {
System.out.println("Scaled image has not yet been created");
}
}
public void saveOriginalImage(File file, ImageType imageType) {
if (originalImage != null) {
BufferedImage bi = new BufferedImage(originalImage.getIconWidth(), originalImage.getIconHeight(), BufferedImage.TYPE_INT_RGB);
Graphics g = bi.getGraphics();
g.drawImage(originalImage.getImage(), 0, 0, null);
try {
ImageIO.write(bi, imageType.value(), file);
} catch (IOException ioe) {
System.out.println("Error occured saving original image");
}
} else {
System.out.println("Original image has not yet been created");
}
}
// ENUMS
public enum ScalingDirection {VERTICAL, HORIZONTAL};
public enum ScaleType {FIT, FILL};
public enum ImageType {
IMAGE_JPEG ("jpeg"),
IMAGE_JPG ("jpg"),
IMAGE_PNG ("png");
private String value = null;
ImageType(String value) {
this.value = value;
}
String value() {
return value;
}
};
}
答案 3 :(得分：1)
请检查一下Image.getScaledInstance（）详细信息可以在这个答案中找到：How to improve the performance of g.drawImage() method for resizing images
希望有所帮助
答案 4 :(得分：1)
public static BufferedImage resizeImg(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;
}
答案 5 :(得分：1)
我推荐Thumbnailnator因为它比Java多步骤方法给了我更高质量的图像。然而，使用Graphics2D drawImage代码的速度可能更好。
答案 6 :(得分：0)
事实上，解决方案更加简单。您不必创建新的BufferedImage。您可以将for3st提到的方法直接应用于原始BufferedImage图像（＆＃39;图像＆＃39;）并设置您希望的宽度和高度。因此，只需要一个语句（包含在stadard Java文档中）：
drawImage(BufferedImage image, int x, int y, int width, int height, ImageObserver observer)