Iris color and texture: A comparative analysis of real irises, ocular prostheses, and colored contact lenses

Abstract

In this work, we analyzed the color and texture of irises, ocular prostheses, and cosmetic colored contact lenses measured by means of a multispectral system, which provides the CIE L*a*b* colorimetric coordinates of a high resolution image pixel by pixel. The same subject, who has dark brown irises, participated in the measurement of all the contact lenses. The CIE L*a*b* colorimetric coordinates were analyzed to classify the samples into three major groups (brown, blue and green) using a new algorithm developed for this purpose. This classification allowed us to carry out a comparison of the color associated with each set of samples, using the corresponding color gamuts in the CIE L*a*b* color space. Furthermore, we analyzed the iris color reproduction achieved by prostheses and contact lenses in terms of CIEDE2000 color differences, and obtained closer results with prostheses. In addition, we performed an analysis of texture by means of the color spatial distribution of all samples. This was achieved by means of two statistical approaches: first order statistics of image histograms and second order statistics using co-occurrence matrices. The results suggest that the texture associated with real irises, ocular prostheses and colored contact lenses is very different. This study provides useful information about the color and texture of irises that may help to establish a strategy for improving the techniques used in the manufacturing process of prostheses and colored contact lenses to obtain a better and more realistic appearance.

Influence of different disinfecting solutions on the color change of artificial irises used in ocular prostheses

“…The ultraviolet visible reflection spectroscopy allows evaluating the absorbed and transmitted radiation of chemicals . In the ocular prosthesis area, the spectrophometric analysis can be used to assess the color stability of organic compounds such as artificial iris oil paint and inorganic materials (i.e., acrylic resin) . The absorption of ultraviolet radiation both visible and infrared depends on the structure of material's molecule which reflects on the color and brightness of the material …”

“…1 In the ocular prosthesis area, the spectrophometric analysis can be used to assess the color stability of organic compounds such as artificial iris oil paint and inorganic materials (i.e., acrylic resin). 2,3 The absorption of ultraviolet radiation both visible and infrared depends on the structure of material's molecule which reflects on the color and brightness of the material. 2,3 In the ocular rehabilitation, the artificial irises are recovered with colorless resin.…”

“…2,3 The absorption of ultraviolet radiation both visible and infrared depends on the structure of material's molecule which reflects on the color and brightness of the material. 2,3 In the ocular rehabilitation, the artificial irises are recovered with colorless resin. 4 Through translucency of prostheses, an adequate shape and volume for the colorless acrylic resin layer of the iris can create the appearance of depth and naturalness that closely resemble the natural eye.…”

Graininess characterization by multidimensional scaling

“…Finally, the measuring parameters calculated with the gonio-hyperspectral system were compared with the two dimensions obtained in MDS. In particular, the system provided first-and second-order statistics, such as entropy, energy and asymmetry for the first order (21)(22)(23)(24), and contrast, correlation, energy and homogeneity for the second order (21)(22)(23)(24)(25). Before studying any correlation, the Procrustes rotation method was applied to the D1/D2 space to optimize the alignment between parameters.…”

Hyperspectral optical imaging of human iris in vivo: characteristics of reflectance spectra

“…29 Previous works have shown the applicability of multispectral imaging in iris recognition systems [30][31][32][33] and iris colorimetry. 27 Vilaseca et al 27,34 measured the iris reflectance using a motorized filter wheel from 400 to 700 nm in steps of 50 nm. The results of a principal component analysis (PCA) suggest that three principal components can account for more than 99% of the total variance across a large number of measured irises, 27 and therefore only three well-defined colorants are sufficient to describe their spectral and chromatic variability.…”