According to the ACRL Visual Literacy Competency Standards for Higher Education:
Visual literacy is a set of abilities that enables an individual to effectively:
Visual literacy skills equip a learner to understand and analyze the:
http://www.ala.org/acrl/standards/visualliteracy
Images and visual interpretations of information and data (charts, infographics) are great ways to engage your audience or reader and convey your message. Before you choose, edit, or create an image, think about what your visual need. What is the purpose of the image? What is the audience and environment? Will you use this image...
in a presentation?
Summit High School Presentation by Tom Sulcer (CC-BY 3.0)
in a paper?
FileStack retouched by Niklas Bildhauer (CC BY-SA 2.0
to be shared online?
Internet1 by Rock1997 (CC BY-SA 3.0)
This will matter when you are evaluting image sources, technical components, copyright status, and design of the image.