# Windows – Invisible PNG image layer that is only visible as a background

I have recently came across a very peculiar image, with strange properties. The image is in PNG format and just shows a simple bird with a transparent background. My friend sent me the image with simple instructions just to save it and set it as my background.

After setting the image as my background a second image appears to show that in fact the seagull standing on a weapon:

This at first got me very curious to the nature of the image and how to make such an image. I have opened the image in Photoshop and nothing out of the ordinary appears – the image is still the same as the transparent seagull, there is no hidden layers or masks to make it invisible. After checking the image in Photoshop, I had thought Windows made changes to the file when setting it as my desktop background – after navigating to %AppData%\Microsoft\Windows\Themes the image appeared to be the same.

Why does this image show a separate hidden layer or a completely separate image when set as a Windows Desktop Background compared to being viewed or edited in Photoshop?