CODE: GitHub
DATATYPE: images
SOURCE: Leonardo Journal, MIT Press
YEARS: 1968-2016
SIZE: 7,072
VIZTYPE: flat histogram
FEATURES: issue, channels, brightness
FEAT SRC: metadata, scikit-image
BINS: 52

This is a "flat histogram", an image histogram where each bin is forced to a fixed height. Normally, histogram bins are fixed "width", meaning they cover the same range of the distribution variable. Here, the bins are fixed height, and thus the variable ranges they cover are unknown (without additional markings on the plot, which is of course a possible modification here). Note that the flat histogram would be perfectly useless for traditional statistical plotting, but since we are making image histograms, they can reveal a lot. The left-to-right visual patterns do still map roughly to the distribution variable. In this plot, the distribution variable is "issue" — i.e., which journal issue the image belongs to — which means that, left-to-right, we have a chronological progression (and since most years / issues are roughly equal in size, this doesn't badly distort the proportionality of the plot). The images are further sorted within each column by number of color channels (which separates the color images from the black-and-white) and brightness. We learn, among other things, that the journal had an explosion of color imagery, followed by a backpedaling and move to very dark images.