我已经尝试过在SO上发布的多个图像调整库,以及使用getScaledInstance的raw
java.虽然一切都在大部分时间工作,但是有两个jpeg图像,每当调整大小时,颜色总是被弄乱.
结果：
第二张图片：
结果：
我已经尝试过这些图像与多个库,包括Scalr,Thumbnailator和raw java使用image.getScaledInstance()(参见here代码),但结果是一样的.
任何想法是什么问题？
解决方法
我找到了一个解决方案,从
this answer的很多帮助：
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.RenderingHints;
import java.awt.Toolkit;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.JPanel;
public class ImgUtility
{
/**
* Takes a file,and resizes it to the given width and height,while keeping
* original proportions. Note: It resizes a new file rather than resizing
* the original one. Resulting file is always written as a png file due to issues
* with resizing jpeg files which results in color loss. See:
* https://stackoverflow.com/a/19654452/49153
* for details,including the comments.
*
*/
public static File resize(File file,int width,int height) throws Exception
{
Image img = Toolkit.getDefaultToolkit().getImage( file.getAbsolutePath() );
loadCompletely(img);
BufferedImage bm = toBufferedImage(img);
bm = resize(bm,width,height);
StringBuilder sb = new StringBuilder();
sb.append( bm.hashCode() ).append(".png");
String filename = sb.toString();
File result = new File( filename );
ImageIO.write(bm,"png",result);
return result;
}
public static BufferedImage toBufferedImage(Image img)
{
if (img instanceof BufferedImage)
{
return (BufferedImage) img;
}
BufferedImage bimage = new BufferedImage(img.getWidth(null),img.getHeight(null),BufferedImage.TYPE_INT_ARGB);
bimage.getGraphics().drawImage(img,null);
bimage.getGraphics().dispose();
return bimage;
}
public static BufferedImage resize(BufferedImage image,int areaWidth,int areaHeight)
{
float scaleX = (float) areaWidth / image.getWidth();
float scaleY = (float) areaHeight / image.getHeight();
float scale = Math.min(scaleX,scaleY);
int w = Math.round(image.getWidth() * scale);
int h = Math.round(image.getHeight() * scale);
int type = image.getTransparency() == Transparency.OPAQUE ? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;
boolean scaleDown = scale < 1;
if (scaleDown) {
// multi-pass bilinear div 2
int currentW = image.getWidth();
int currentH = image.getHeight();
BufferedImage resized = image;
while (currentW > w || currentH > h) {
currentW = Math.max(w,currentW / 2);
currentH = Math.max(h,currentH / 2);
BufferedImage temp = new BufferedImage(currentW,currentH,type);
Graphics2D g2 = temp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2.drawImage(resized,currentW,null);
g2.dispose();
resized = temp;
}
return resized;
} else {
Object hint = scale > 2 ? RenderingHints.VALUE_INTERPOLATION_BICUBIC : RenderingHints.VALUE_INTERPOLATION_BILINEAR;
BufferedImage resized = new BufferedImage(w,h,BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = resized.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,hint);
g2.drawImage(image,w,null);
g2.dispose();
return resized;
}
}
/**
* Since some methods like toolkit.getImage() are asynchronous,this
* method should be called to load them completely.
*/
public static void loadCompletely (Image img)
{
MediaTracker tracker = new MediaTracker(new JPanel());
tracker.addImage(img,0);
try {
tracker.waitForID(0);
} catch (InterruptedException ex) {
throw new RuntimeException(ex);
}
}
}