I get what you mean.
The fabric of space-time itself could contain the pixels. Looking at crystals on an atomic scale, how did you determine that what you are seeing is continuous in nature and not a summation of discretely sized subsections?
Atoms and particles are discretely-sized subunits. In crystals, they even order themselves. But they don't have the other properties of pixels. They're not displaying an image or a dataset brought in from "elsewhere". They're just sitting there in their discreet ordered way.
Doesn't every photon that enters our eye exist between some minimum and maximum energy values, dictated by the laws of physics?
Yes. But how does that relate to pixels?
<edit> on reconsideration, No. Gamma and radio enter our eyes as well ... we just don't see them. "How relate to pixels?" question still stands, though.
How did you determine that the images you see in real life are not from inconceivably small pixels? Just imagine a high definition tv that is many many orders of magnitude better than current technology, and the screen can be shaped into a 3-d object. How do you distinguish between a real person, and an apparent person on a 3-dimensional screen with a resolution higher than you can detect? No matter how closely you magnify the screen you see what appears to be a continuous picture.
Indirectly. I've always been a keen student of the world of the very small. Atoms and subatomic particles don't have the digital data representation that gives pixels their meaning. They're so relentlessly analog. Even quantization isn't digitization, to the chagrin of the quantum information buffs.
For the fabric of the universe to be made of pixels, they'd have to be smaller than the Planck length and refresh faster than the Planck duration. Since those Planck quantities are considered the limit of meaningful properties, the problem has been shunted aside into metaphysics as far as I'm concerned.
What drew my interest was OP's claim of seeing pixels in nature. The only ones I can envision would be
beneath nature and its Planck limit. Sorta not the same thing imo. cn