Before entering the question let me try to state an acceptable definition of what we, humans, mean for truth. Staying with the 'Tao Te Ching' truth may be derived from the not true. In general truth is defined on the basis of a shared acceptance or common sense and tied to what is considered not/un true in relation to a context.
Back at the times when photography was invented in the western culture context the shared convention about truth was a lot different from ours. The belief in an absolute Truth was strong. A strange monster made by Enlightenment rationality and Religious observance (or prudent ostentation).
If we look into to those times we can find for example that, more or less in the same times, Boole made some very bold statements about Truth. It will be called, later, Boolean logic. Since the Greeks (and if we stay with the ``Concise history of Mathematics'' even before by people in India), logic has been a model for rigorous reasoning. Axioms and rules to infer from them. At the time the dominant science, physics tended to an axiomatic form (or just got there). By the end of the century relativity and other development in physics and mathematics made some treats to logic and even more to the idea of a universal Truth. This lent to the development of a logic (or theory of truth) strongly based upon formal models against which formulate evaluable assertions. To put it briefly truth becomes relative to the model in which it is formulated, it follows that the model itself must be evaluable or at least fully given. A solution adopted in Humanistic sciences is the one from Popper where a theory to be considered science must at least declare what either is outside the scope of the model or could falsify it (this is to put it in a very simple way. Forgive me for the brevity).
In natural sciences the thing were a bit more funny, in the first half of the 19th, as for the attempts to calculate the age of the earth on the Genesis' base. In that segment the idea of Truth as being one and supreme constituted a strong model.
But what does it mean for photography in general ? A picture is a model in itself. I would say that it is a model of a perceived reality, the photographer's one. As a model it is, by definition, a simplification of the modeled. As a model it has a constraint from which there is no escape: linear perspective, without it there would be no photography, at least not in the known sense. From the constraint it follows that photography at large can only be a model for assertions in the Euclidean world. Color, including shades of gray, is an other strong constraint in the model, but here we have a rather undeveloped area of knowledge and a whole argument in itself, and truth, here, has a very limited reach to be useful. Truth, in color, can only be derived from the Pantone reference ? And which place has the color picked value ? Is my (3)A 2B (light green) truer than yours ?