mat对象作为字节数组与jpg格式有什么区别？

Question

I save the Mat object as byte array:

public static void save(Mat mat, String name)
{
    File file = new File(path, name);
    int length = (int) (mat.total() * mat.elemSize());
    byte buffer[] = new byte[length];
    mat.get(0, 0, buffer);
    try
    {
        FileUtils.writeByteArrayToFile(file, buffer);
    } catch (IOException e)
    {
        e.printStackTrace();
    }
}

and I save via Imgcodecs.imwrite(); but the file size is very different: the JPG file size is less than 100kb but the byte file size is more than one megabyte.

Why is the second file so much bigger?

Answer 1

The first file is an actual compressed image file. The second file is simply a byte array, which is not compressed and therefore contains more data and is bigger.

Check the links below, they explain in further depth what image compression means and the difference between lossy compression and lossless compression.

• http://www.ams.org/samplings/feature-column/fcarc-image-compression
• http://www.debugmode.com/imagecmp/