我猜这与这个问题有关：生成的图片显示翻转

I'd guess this is related to this question: Generated images showing flipped

iPad相机可能只是以相同的方式存储图像，无论设备方向如何，而是写一个Exif标签以确保它在显示时正确旋转。

The iPad camera probably just stores the image in the same way, regardless of device orientation, and instead writes an Exif tag to make sure it's properly rotated when displayed.