APK files for use in a Android Smartphone in this kind of optical illusion: https://www.youtube.com/watch?v=s4FehKoPEgs and here: https://www.youtube.com/watch?v=5PrK-y1Eaqo , called "Pepper's Ghost" after John Henry Pepper who who popularized the effect in a famed demonstration in 1862. However this optical illusion was actually invented much earlier, by the Italian polymath and original Renaissance man Giambattista della Porta in 1584, and is undergoing a bit of a revival in our own screen-dominated culture, with many people making it themselves often out of ordinary clear plastic! Although "hologram" is often found in the title of these kinds of display systems - they technically have no holographic qualities. A hologram refers to a specific medium that stores image data through a laser, a holographic substrate, (such as a photographic film or plate), and an interference pattern. Pepper's Ghost uses a much simpler technique that merely reflects an image off of a surface to create an illusion of a 3D object floating in physical space. In my version, I have decided to spray the pyramid with some SiO2 nanoparticles in solution to reduce fogging on the plastic. What makes it work however is the 4-way images on the phone or digital picture frame screen that have had brightness and contrast enhanced to counter the fact that during the reflection of light off of each side of the frame you are reducing the light intensity by 50% - hence the light intensity and contrast have to be increased by up to 50% to enhance the effect and make the effect look more than a mere reflection and appear as if the object is indeed inside the pyramid, floating in mid air. GIF images with 4-faces of an object can give a better ability to broaden the range of holographic art. Commercial digital photo frames can then be turned into holographic photo frames with this simple add-on modular device.
