Abstract: Previous historical and philological commentaries on Nostradamus' "Prophecies" by Prof. Brind'Amour, R. Prevost, P. Guinard, A. Penzensky, and D. Crouzet have led to the unexpected conclusion that many quatrains are uninformative as predictions; moreover, some of them describe events preceding the moment of publication, raising questions about the predictor's motivation. Against the background of the increased interest in the development of cryptology methods in the first half of the 16th century, it is appropriate to assume the existence of a hidden message in the "Prophecies". Recent work by the author has shown that the text of the "Prophecies" contains two types of cipher. The modified algorithm "scytale" is apparently used to change the sequence of quatrains and assign them certain dates of real time. Additionally, a large graphical cipher is invisibly embedded in the text, so that specific words or letters, when mapped as stains on a plane in the coordinates "century number – quatrain number", lead to images of human faces. These images likely serve as illustrations to the prophetic text, however, their low quality and the cipher author's tendency towards surrealism make it difficult to identify the characters. The aim of this work is to propose a new method for processing the raw data to obtain higher-quality images, called the "smooth assembly" method, and to discuss Nostradamus' graphical cipher in a historical context. The results of the study suggest that Nostradamus' graphical cipher was a unique experiment in embedding images in text and had significant scientific value for the development of steganography in the 16th century. This leads to the assumption that, in addition to predictive motivation (or instead of it), the cipher author pursued a purely scientific goal – the creation of a new promising method of covert information transmission.