压缩JPG使图像变绿
当我尝试压缩 jpg 图像时，大多数情况下它都能正常工作，但是有些 jpg 图像在压缩后会变成绿色。这是我的代码
public void compressImage(String filename, String fileExtension) {
BufferedImage img = null;
try {
File file = new File(filename);
img = ImageIO.read(file);
if (fileExtension.toLowerCase().equals(".png") || fileExtension.toLowerCase().equals(".gif")) {
//Since there might be transparent pixel, if I dont do this,
//the image will be all black.
for (int x = 0; x < img.getWidth(); x++) {
for (int y = 0; y < img.getHeight(); y++) {
int rgb = img.getRGB(x, y);
int alpha = (rgb >> 24) & 0xff;
if (alpha != 255) {
img.setRGB(x, y, -1); //set white
}
}
}
}
Iterator iter = ImageIO.getImageWritersByFormatName("jpg");
//Then, choose the first image writer available
ImageWriter writer = (ImageWriter) iter.next();
//instantiate an ImageWriteParam object with default compression options
ImageWriteParam iwp = writer.getDefaultWriteParam();
//Set the compression quality
iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
iwp.setCompressionQuality(0.8f);
//delete the file. If I dont the file size will stay the same
file.delete();
ImageOutputStream output = ImageIO.createImageOutputStream(new File(filename));
writer.setOutput(output);
IIOImage image = new IIOImage(img, null, null);
writer.write(null, image, iwp);
writer.dispose();
} catch (IOException ioe) {
logger.log(Level.SEVERE, ioe.getMessage());
}
}
When I try to compress the a jpg image, most of the time it work perfectly, however some jpg image turn green after the compression. Here is my code
public void compressImage(String filename, String fileExtension) {
BufferedImage img = null;
try {
File file = new File(filename);
img = ImageIO.read(file);
if (fileExtension.toLowerCase().equals(".png") || fileExtension.toLowerCase().equals(".gif")) {
//Since there might be transparent pixel, if I dont do this,
//the image will be all black.
for (int x = 0; x < img.getWidth(); x++) {
for (int y = 0; y < img.getHeight(); y++) {
int rgb = img.getRGB(x, y);
int alpha = (rgb >> 24) & 0xff;
if (alpha != 255) {
img.setRGB(x, y, -1); //set white
}
}
}
}
Iterator iter = ImageIO.getImageWritersByFormatName("jpg");
//Then, choose the first image writer available
ImageWriter writer = (ImageWriter) iter.next();
//instantiate an ImageWriteParam object with default compression options
ImageWriteParam iwp = writer.getDefaultWriteParam();
//Set the compression quality
iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
iwp.setCompressionQuality(0.8f);
//delete the file. If I dont the file size will stay the same
file.delete();
ImageOutputStream output = ImageIO.createImageOutputStream(new File(filename));
writer.setOutput(output);
IIOImage image = new IIOImage(img, null, null);
writer.write(null, image, iwp);
writer.dispose();
} catch (IOException ioe) {
logger.log(Level.SEVERE, ioe.getMessage());
}
}
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评论（3）
将最终图像从
YUV转换回RGB，将恢复图像的颜色。此转换对我有用：
cv2.cvtColor(img_file, cv2.COLOR_YUV2RGB)Converting the final image from
YUVback toRGB, will restore the colors of the image.This conversion worked for me:
cv2.cvtColor(img_file, cv2.COLOR_YUV2RGB)根据经验，我知道绿色是新格式化的 YUV 内存（特别是 YV12）的颜色。所以我的猜测是某个步骤失败了，你得到了亮度信息，但色度被破坏了。在我看来，它在到达 Cr 飞机之前就失败了。
无论如何，祝你好运，这很难。不过你的代码看起来很奇怪——顶部奇怪的 png 特定代码是怎么回事？ AFAIK，如果您使用 .NET，您几乎可以将任何注册的图像格式视为没有任何有趣工作的图像。
From experience, I know that green is the color of freshly formatted YUV memory (YV12, in particular). So my guess is some step is failing, and you get luma information but the chroma gets botched. Looks to me like it's failing before it gets to the Cr plane.
Anyway, good luck, that's a tough one. Your code looks strange though--what's with the weird png specific code at the top? AFAIK, if you're using .NET you can pretty much treat any registered image format just as though it's an image without any funny work.
我有同样的问题。在我的测试服务器中运行 java 7 oracle 并且工作正常。在我的生产服务器中运行 openJDK 1.7，压缩图像变成绿色...这似乎是某些 JAVA 版本中的错误。
I have the same problem. In my test server run java 7 oracle and work fine. In my production server run openJDK 1.7, and compress images turn green...It´s seems bug in some JAVA versions.