The contrary case can be put.
Photographs, unique among known picture making processes, are securely immune from the hazard of illusion. All other pictures, paintings, drawings, and digipix, are generated from coded descriptions stored in a brain, either a human brain or a computer brain. And to change the picture all that is needed is to change the description. This is freely possible without reference to any external reality.
Photographs, on the other hand, are initiated by a physical sample of subject matter penetrating a light sensitive surface and occasioning in situ marks. This pattern of marks, the photograph, arises via the impersonal operation of the laws of chemistry and physics. A photograph is never virtual. A typical 8x10 photograph (for example) weighs about 15.7 grammes and is 0.28mm thick. An honest photograph is inherently incapable of depicting figments of the imagination or hallucinations. The other picture making processes, paintings, drawings, digipix, and what have you, promise that whatever can be thought of can be depicted. Here is a dramatic and decisive difference that sets photography apart.
None of this argument closes off the richness and perversity of the human imagination. People are free to entertain their own illusions, delusions, misinterpretations, and hallucinations about photographs as with any other aspect of the material world.