从Java中的非常大的图像文件中读取区域

Question

是否有一个Java库可以读取非常大的图像(例如JPEG)文件(> 10,000 x 10,000像素)的区域,而不会将整个图像保留在内存中.

或者,哪个Java库能够以最小的开销处理非常大的图像文件.

Answer 1

标准ImageIO允许您读取(大)图像的区域,而无需先将整个图像读入存储器.

Rectangle sourceRegion = new Rectangle(x, y, w, h); // The region you want to extract

ImageInputStream stream = ImageIO.createImageInputStream(input); // File or input stream
Iterator<ImageReader> readers = ImageIO.getImageReaders(stream);

if (readers.hasNext()) {
    ImageReader reader = readers.next();
    reader.setInput(stream);

    ImageReadParam param = reader.getDefaultReadParam();
    param.setSourceRegion(sourceRegion); // Set region

    BufferedImage image = reader.read(0, param); // Will read only the region specified
}