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Trying to Identify a Technique

I recently attending an art show. One artist featured photos that appeared to change based on the angle at which they were viewed. For instance, there was a photo of a tree. From one angle, it was a summer scene. The tree was leafy. From another angle, it was a winter scene. The tree was bare. I've tried googling this, but haven't been able to determine how this is done. Any input would be appreciated.