# Which one is the real car and which one is the reflection?

I think photo above is one of the best photos in the world. See once, then turn the image around 180°, then see again...

Which one is the real car and which one is the reflection? How can you tell?

• @mattdm In fact yes I'm newbie in determining which is the reflection. looks like the picture with the car at the top of the frame is the correct one. Am I right? Jul 24, 2016 at 16:14
• Be aware that Stack Exchange hates fun.... Jul 24, 2016 at 16:28
• @mattdm I meant was turn around 180° Jul 24, 2016 at 16:30
• You may find this example to be of interest. I purposefully did not remove some "visual clues" which make it far easier to decide 'which way is up'. Jul 24, 2016 at 23:53

It's hard to tell with this low quality of image (and one which has presumably undergone some degree of post-processing), but at first glance it appears that the image is not inverted; the reflection in water is below and the real sky is above. That's because it would be quite odd for the water to be brighter than the sky — and because without prompting, one doesn't have much reason to look more than once.

But if one does take a second look, the geometry of the "above" section doesn't look right; I can't imagine how the tires would work. That makes more sense as a reflection (with a sandbar or something in the middle). And it makes the rocks to the side of the frame make sense, too — they're further out in the water, which is at a long angle. Also that little thing which looks like an old-school telephone is a branch or something hooking a little bit out of the water — if that were the sky, the only thing that would make sense is it being part of a larger object which is otherwise obscured, and that seems unlikely.

The angle also explains the difference in brightness — the background below is hills or something in the background, not the sky.

All of this becomes blindingly obvious if one rotates the image back to its actual original orientation:

So, that leaves the question: why is it ambiguous when inverted, but immediately obvious in the correct orientation?

The brain didn't evolve to process impossible situations; it takes input from the senses and assumes that it's correct, and tries to make a rational model of the world from it. So, when we look at the inverted image, there is a fundamental unconscious assumption that seeing is believing. One has to intentionally examine the details to tease out the possibility that it's not right. Even though those details make no sense, you're working against your brain doing its normal job.

In addition to the simple expectation that "up is up", there's an inherent assumption of perspective — that the landscape (or in this case, water) recedes in the center of the frame. In the correct orientation, that is indeed true. But flipped around, it becomes difficult to visualize the angle of the water coming towards us — even when you know for sure that it does from looking at the other view, the brain really wants to make it into at least a vertical view of rocks and bushes right on the bank.

Turned the correct way, it's a humdrum photo with not that much interest, so I guess if there's any general lesson for photography, it's that creating uncertainty and messing with those fundamental assumptions definitely does lend interest.

On the comment "one of the best photos in the world" — well, there's no arguing with opinions. But it would certainly be possible to stage or discover a situation where the shoreline, lighting, and angle make reflection vs. reality even more ambiguous.

• Conversely, it would be impossible for a reflection to be brighter than the object it reflects. On a perfect mirror, they would be almost equal but any other reflector would lose some light.
– Itai
Jul 24, 2016 at 16:21
• @Itai Definitely — the brighter car below (in the inverted version) is a clue (and the darker background a red herring). Jul 24, 2016 at 16:42
• @Itai you're right on the physics requiring loss of photons through a reflection, but... just to fly my pedantic jerk colors, it's easily possible to create a photo (without post-processing) where the reflection appears brighter than the object: reverse or hard ND graduated filter. =)
– scottbb
Jul 24, 2016 at 21:19