图像大小调整：调整大小后原始颜色已更改

Question

我正在使用Play！Framework 1.x，其中一个有用的工具是类Images，它允许我动态调整图像大小。

以下是Images.resize的代码：

/**
 * Resize an image
 * @param originalImage The image file
 * @param to The destination file
 * @param w The new width (or -1 to proportionally resize) or the maxWidth if keepRatio is true
 * @param h The new height (or -1 to proportionally resize) or the maxHeight if keepRatio is true
 * @param keepRatio : if true, resize will keep the original image ratio and use w and h as max dimensions
 */
public static void resize(File originalImage, File to, int w, int h, boolean keepRatio) {
try {
    BufferedImage source = ImageIO.read(originalImage);
    int owidth = source.getWidth();
    int oheight = source.getHeight();
    double ratio = (double) owidth / oheight;

    int maxWidth = w;
    int maxHeight = h;

    if (w < 0 && h < 0) {
        w = owidth;
        h = oheight;
    }
    if (w < 0 && h > 0) {
        w = (int) (h * ratio);
    }
    if (w > 0 && h < 0) {
        h = (int) (w / ratio);
    }

    if(keepRatio) {
        h = (int) (w / ratio);
        if(h > maxHeight) {
            h = maxHeight;
            w = (int) (h * ratio);
        }
        if(w > maxWidth) {
            w = maxWidth;
            h = (int) (w / ratio);
        }
    }

    String mimeType = "image/jpeg";
    if (to.getName().endsWith(".png")) {
        mimeType = "image/png";
    }
    if (to.getName().endsWith(".gif")) {
        mimeType = "image/gif";
    }

    // out
    BufferedImage dest = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
    Image srcSized = source.getScaledInstance(w, h, Image.SCALE_SMOOTH);
    Graphics graphics = dest.getGraphics();
    graphics.setColor(Color.WHITE);
    graphics.fillRect(0, 0, w, h);
    graphics.drawImage(srcSized, 0, 0, null);
    ImageWriter writer = ImageIO.getImageWritersByMIMEType(mimeType).next();
    ImageWriteParam params = writer.getDefaultWriteParam();
    FileImageOutputStream toFs = new FileImageOutputStream(to);
    writer.setOutput(toFs);
    IIOImage image = new IIOImage(dest, null, null);
    writer.write(null, image, params);
    toFs.flush();
    toFs.close();
    writer.dispose();
} catch (Exception e) {
    throw new RuntimeException(e);
}

}

以下是我如何使用它：

File old = new File("1.jpg");
File n = new File("output.jpg");
Images.resize(old, n, 800, 800, true);

原始图片1.jpg：

output.jpg：

有谁可以解释这里发生了什么？谢谢！

Answer 1

我也看过这个，并且相信这是一个JRE错误。我通过不使用getScaledInstance而不是scaling while drawing来解决这个问题。

Answer 2

阿。我太慢了回答。但是，是的，它很可能是一个错误。我自己遇到了这个问题。你必须解决它。尝试按照Waldheinz的说法缩放图像。这也是我做的。

这是我用来进行缩放的链接：http://www.rgagnon.com/javadetails/java-0243.html，所以你在waldheinz的参考资料中有更多的参考资料