Earlier quoted context omitted.
You're talking about two different things. One is an illusion, or the set of all illusions, and the other is the set of all images generated by pixels. Not all images generated by pixels are an illusion. Otherwise you would say that all images generated by, say, acrylic paint, are an illusion because they're made of molecules.
That we perceive paintings of objects as objects is an illusion, clearly. But that is not the same illusion as this "pigeon neck" thing. An illusion is not an illusion if what you perceive is what is actually happening. The whole point of the "pigeon neck" illusion is that it tricks the eye into perceiving areas as growing that we know are incapable of growing. If the areas are inelastic matter, that's a cool effect:…
There is, objectively, data being presented, which we perceive.
You're glossing over the importance of a particular scale, the scale at which humans operate in on a daily basis, and making the assumption that reality is what's happening at a smaller scale.
This is incomplete.
If we want to talk about the image, the underlying components become progressively less important as the scale decreases. When we view a painting, or an image on a screen, when are less interested in up quarks, down quarks, and electrons, and more interested in the image and the medium.