将小图像合并为一张图像，而不在内存中分配完整图像

发布于 2024-10-20 02:31:40 字数 1405 浏览 2 评论 0原文

我必须用java制作一个并行图像处理脚本，其想法是将图像划分为任意大小的图块，处理它们，然后重新组合最终图像。

现在我创建了一个函数：

public static BufferedImage readImg (String path, int startx, int starty, int w, int h)

将图像区域返回为 BufferedImage，然后我将处理它，并且我想将该区域放置在最终图像的正确位置。

所以我尝试创建一个函数 writeImg ，它使用 ReplacePixels 方法在正确的位置写入，而不将整个图像加载到内存中：

public static void writeImg (String path, int startx, int starty, BufferedImage image){
    File output = new File(path);
    ImageOutputStream ios = null;
    try {
        ios = ImageIO.createImageOutputStream(output);
    } catch (IOException e){
        e.printStackTrace();
    }
    Iterator iter = ImageIO.getImageWritersByFormatName("JPEG");
    ImageWriter writer = (ImageWriter)iter.next();
    writer.setOutput(ios);

    try{
        if(writer.canReplacePixels(0)){
            System.out.println("True");
        }else{
            System.out.println("False");
        }
    }catch (IOException e) {
        e.printStackTrace();
    }

    ImageWriteParam param = writer.getDefaultWriteParam();
    Point destinationOffset = new Point(startx,starty);
    param.setDestinationOffset(destinationOffset);
    try {
        writer.replacePixels(image, param);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

问题是 canReplacePixels 始终设置为 false，我不知道应该使用什么这样做。

图像可能非常大，因此不可能将整个图像加载到内存中，因为这会导致 OutOfMemory 异常。

原文

I've to make a parallel image processing script in java, the idea is to divide the images into tiles of any size, process them, and reassemble the final image.

For now i've created a function:

public static BufferedImage readImg (String path, int startx, int starty, int w, int h)

that returns the region of an image as BufferedImage, then i'll process it and i want to place that region in the correct position of the final image.

So i've tried to make a function writeImg that uses replacePixels method to write just in the correct position without loading the whole image into memory:

public static void writeImg (String path, int startx, int starty, BufferedImage image){
    File output = new File(path);
    ImageOutputStream ios = null;
    try {
        ios = ImageIO.createImageOutputStream(output);
    } catch (IOException e){
        e.printStackTrace();
    }
    Iterator iter = ImageIO.getImageWritersByFormatName("JPEG");
    ImageWriter writer = (ImageWriter)iter.next();
    writer.setOutput(ios);

    try{
        if(writer.canReplacePixels(0)){
            System.out.println("True");
        }else{
            System.out.println("False");
        }
    }catch (IOException e) {
        e.printStackTrace();
    }

    ImageWriteParam param = writer.getDefaultWriteParam();
    Point destinationOffset = new Point(startx,starty);
    param.setDestinationOffset(destinationOffset);
    try {
        writer.replacePixels(image, param);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

The problem is that canReplacePixels is always set as false, and i've no idea what should i use to do that.

The images can be very big so it's impossible to load the whole image in memory as it will cause a OutOfMemory exception.

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