The phrase "visual literacy" is one that is often bandied about these days, and has begun to grate on my nerves a bit — if only because it is a bit vague and vacuous in meaning. The phrase at this point is basically being used to mean a familiarity with anything that is an image and (usually) not text.
However, what kind of "literacy" is this exactly? The range of things covered by this term include vastly disparate material: diagrams, paintings, graphs, websites, comics, etc.
Not all of these items are processed in a similar way, and "literacy" for one does not necessarily equate with "literacy" for another. For example, I know people who are highly fluent in reading the visual language of comics, yet find "infographics" like flow charts mind-numbingly opaque (and vice-versa).
Such a phrase implies 1) that visual communication and expression is homogenous, and any diversity is washed over by its shared virtue of being "visual", and 2) that comprehension of one of these forms equates to or leads to equal understanding of the others.
This seems far from the case. The various things that are covered by this term have very different motivating structures and properties, and comprehension with one does not necessarily lead to the same skills with others (and especially does not imply that for production). Really, what we have is a number of disparate forms that each involve their own forms of fluency independently, despite a shared visual modality.
The implication that such diversity is homogenous is a kind of orientalism — likely just a view embodied from a culture entrenched in a verbal modality that is still grasping at a method of communication that it doesn't yet fully embrace or understand.