How to know whether an image is flipped

[Lizhuoling]

Hi, I notice that random horizontal flip is applied during the training process. Although the image is flipped, the camera intrinsics returned by the data loader does not be changed accordingly. So, I need to transform the intrinsics by myself. However, I cannot find where the random horizontal flip is performed, so I cannot know whether an image is flipped. Can you give some reminder? Where I can know whether an image is flipped?