Images from different spectral bands are utilized to construct the hypercomplex space.
Longbin Lu, Xinman Zhang, Xuebin Xu 2019, 'Hypercomplex extreme learning machine with its application in multispectral palmprintrecognition', PLOS ONE10.1371/journal.pone.0209083. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
It utilizes hypercomplex number theory, which has not yet been employed in these areas.
Alexander Petrovsky, Marek Parfieniuk 2007, 'Quaternionic Lattice Structures for Four-Channel Paraunitary Filter Banks', EURASIP Journal on Advances in Signal Processinghttp://dx.doi.org/10.1155/2007/37481. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
The respective hypercomplex numbers turn out to be handy on this occasion.
V. V. Kisil 2011, 'Erlangen Programme at Large 3.2 Ladder Operators in Hypercomplex Mechanics', Acta Polytechnicahttps://ojs.cvut.cz/ojs/index.php/ap/article/view/1402. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)