The Minim Mathematician: Jean-François Niceron (1613–1646)
In 1638, the French Minim friar and mathematician Jean-François Niceron published La Perspective Curieuse, ou Magie Artificielle des Effets Merveilleux. Niceron revealed the secret mathematical rules of catoptric anamorphosis: paintings deliberately warped using polar conformal transformations so they appear as unintelligible chaotic ribbons to the naked eye, yet resolve into exquisite, perspective-correct portraits when viewed in a cylindrical or conical polished mirror.
The Mathematical Coordinate Inversion:
A rectilinear image coordinate $(u, v)$ where $u \in [-\pi, \pi]$ and $v \in [0, 1]$ is projected onto the circular disc in polar coordinates:
θ = u, r = R_cyl + (1 - v)^k · (R_disc - R_cyl)
Where $R_{\text{cyl}}$ is the cylinder mirror radius, and $k \approx 1.2$ compensates for oblique foreshortening of the ground plane.
Historical Espionage & Clandestine Royalist Plates
Following the English Civil War and the execution of King Charles I in 1649, loyalist Cavaliers carried seemingly harmless decorative plates painted with swirling pastoral foliage or marbled clouds. When placed beneath a polished pewter drinking tankard at a tavern table, the reflection secretly revealed the crowned face of the martyred monarch. Similar techniques were used by Jacobite rebels and French Revolutionary conspirators.
How to Test in the Physical World
You can use the Inscriber Atelier to export your own custom anamorphic disc. Print it at 100% scale and place any highly reflective vertical cylinder at the center circle—a polished aluminum soda can, chrome plumbing pipe, or stainless steel shaker. Look down at a 40°–50° angle, and watch your secret cipher magically appear!