ImagePlot is a software which analyzes the brightness, hue and saturation of each image in a data set, and uses it as a basis for the visualization of a whole book collection as an organized display. In this paper, we examine what insights it can give into Cambridge University Library Liberation Collection’s digitized book covers. This collection consists in more than 3000 books and pamphlets in French on the Second World War, the Occupation of France and the Liberation, published between August 1944 and the end of 1946. This article discusses some of the findings and research questions resulting from the use of ImagePlot on this specific set of digitized historical book covers provided with rich metadata. The visualization of the ‘brightness’ of covers from groups of books written by the same authors show how cover illustrations contribute to the visual identity of some juvenile literature series and magazines, even when they are not all produced by the same artist. The visualization of the ‘saturation’ and ‘hue’ of some of these book covers leads into the field of color symbolism and of the aesthetics chosen by some publishers. With our corpus, the ImagePlot visualizations of books covers by year are less easy to interpret in terms of general trends and evolution.