The ability to save images to a 3rd party host is important to my note-taking application as it minimizes the possiblity of overloading the server. I wasn’t sure but it turned out to be “insanely” simple to automatically upload images to imgur - only one line of codes to set an option in knitr.
opts_knit$set(upload.fun = imgur_upload, base.url = NULL)
So when a class of students are all learning histograms using the following codes, the diagram will be stored in imgur.com and not on the server hosting the note-taking application.
hist(nt.1$Word, col = "darkgreen", xlab = "Number of Words", ylab = "Frequency", main = "Histogram - Number of Words Recorded in Lecture Notes")