Computer averaging of electron micrographs of the 405 ribosomal subunit.

Frank and colleagues developed a method that allows sorting of particle images into classes based on their orientation, as well as their structural features. Specifically Frank developed mathematical tools used for image analysis, which form the basis for single particle cryo-EM. He gathered them together in a suite of computer programs called “SPIDER”, making them readily available and useable for the scientific community. Order of authorship in the original publication: Frank, Verschoor, Boublik.

In 2017 Frank shared the Nobel Prize in Chemistry with Jacques Dubochet and Richard Henderson "for developing cryo-electron microscopy for the high-resolution structure determination of biomolecules in solution."

(Thanks to Juan Weiss for this reference and its interpretation.)