我编写这段代码是为了根据两个因素调整图像大小。可以用,但是调整大小后图像质量很差!你能帮帮我吗?
这是代码
public class ImageTest {
private static final int factor1 = 3;
private static final int factor2 = 4;
public static void main(String [] args){
JFileChooser cs = new JFileChooser();
cs.setFileSelectionMode(cs.DIRECTORIES_ONLY);
int i = cs.showOpenDialog(null);
if(i==cs.APPROVE_OPTION){
File f = cs.getSelectedFile();
File[] ff = f.listFiles();
for(int j=0;j<ff.length;j++){
String end = ff[j].getName().substring(ff[j].getName().indexOf(".")+1);
System.out.println(end);
try{
BufferedImage originalImage = ImageIO.read(ff[j]);
int type = originalImage.getType() == 0? BufferedImage.TYPE_INT_ARGB : originalImage.getType();
BufferedImage resizeImageJpg = resizeImageWithHint(originalImage, type);
ImageIO.write(resizeImageJpg, end, new File("pr/"+ff[j].getName()));
}catch(IOException e){
e.printStackTrace();
}
}
}
}
private static BufferedImage resizeImageWithHint(BufferedImage originalImage, int type){
int IMG_WIDTH = (originalImage.getWidth()*factor1)/factor2;
int IMG_HEIGHT = (originalImage.getHeight()*factor1)/factor2;
BufferedImage resizedImage = new BufferedImage(IMG_WIDTH, IMG_HEIGHT, type);
Graphics2D g = resizedImage.createGraphics();
g.drawImage(originalImage, 0, 0, IMG_WIDTH, IMG_HEIGHT, null);
g.dispose();
g.setComposite(AlphaComposite.Src);
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.setRenderingHint(RenderingHints.KEY_RENDERING,
RenderingHints.VALUE_RENDER_QUALITY);
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
return resizedImage;
}
}
我在网上看到 resizeImageWithHint 是在范围内完成的,以免降低质量……但确实如此!为什么?你能帮我吗?
最佳答案
关于这个主题我读过的最好的文章是 The Perils of Image.getScaledInstance() (网络存档)。
简而言之:您需要使用多个调整大小步骤才能获得良好的图像。文章中的辅助方法:
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.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
} while (w != targetWidth || h != targetHeight);
return ret;
}
关于java - 在不损失质量的情况下调整图像大小,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/7951290/