Editing Iris recognition (section)

== Visible vs near infrared imaging ==
Iris [[melanin]], also known as chromophore, mainly consists of two distinct heterogeneous macromolecules, called eumelanin (brown–black) and pheomelanin (yellow–reddish),<ref>{{cite journal |vauthors=Liu Y, Simon JD |title=Metal-ion interactions and the structural organization of Sepia eumelanin |journal=Pigment Cell Res. |volume=18 |issue=1 |pages=42–8 |date=February 2005 |pmid=15649151 |doi=10.1111/j.1600-0749.2004.00197.x }}</ref><ref>{{cite journal |vauthors=Meredith P, Sarna T |title=The physical and chemical properties of eumelanin |journal=Pigment Cell Res. |volume=19 |issue=6 |pages=572–94 |date=December 2006 |pmid=17083485 |doi=10.1111/j.1600-0749.2006.00345.x }}</ref> whose absorbance at longer wavelengths in the NIR spectrum is negligible. At shorter wavelengths within the VW spectrum, however, these chromophores are excited and can yield rich patterns. Hosseini, ''et al.''<ref>{{cite journal |author1=Hosseini, M.S. |author2=Araabi, B.N. |author3=Soltanian-Zadeh, H. |title=Pigment Melanin: Pattern for Iris Recognition |journal=IEEE Trans Instrum Meas |volume=59 |issue=4 |pages=792–804 |date=April 2010 |doi=10.1109/TIM.2009.2037996 |arxiv=0911.5462 |bibcode=2010ITIM...59..792H |s2cid=16646573 }}</ref> provide a comparison between these two imaging modalities. An alternative feature extraction method to encode VW iris images was also introduced, which may offer an alternative approach for multi-modal biometric systems.

{| class="wikitable"
|-
! style="width:230px" | Visible wavelength iris image
! style="width:230px" | Near infrared (NIR) version
! style="width:230px" | NIR imaging extracts structure
|-
| [[File:ColourIris.png|247px]]
| [[File:NIRIris.png|230px]]
| [[File:IRiris.jpg|230px]]
|-
| Visible light reveals rich pigmentation details of an Iris by exciting [[melanin]], the main colouring component in the iris.
| Pigmentation of the iris is invisible at longer wavelengths in the NIR spectrum.<br />&nbsp;
| Even "dark brown" eyes reveal rich iris texture in the NIR band, and most corneal specular reflections can be blocked.
|}