Thank you, and yes, it would be simple to create the image.
Of course I mixed up X and Y in my response. Y shifts vertically and not horizontally (which would use a small vertical band). Sorry about that.
With the large scaling and shifting Y you select a very subtle gradient top to bottom. With a great result!
Of course the same could be tried in the horizontal plane. With the right scaling and placed in the correct way it could suggest movement of the model. A model walking from left to right and the gradient with more transparency on the left and less to the right should do that.

I wonder if this system makes it viable to display a large crowd in a photo rendering. Using normal models with regular textures would take a very long time to render but maybe as ghosts it becomes reasonable.