Color measurement system with color index for skin, teeth, hair and material substances

Abstract

Methods and systems for measuring with a Color Measurement System of predetermined specification and evaluating the color of skin, teeth, hair and material substances with a Color Index. The principles of this invention also relate to techniques for using such a Color Measurement System with the Color Index in medical applications such as the detection of chromogenic disease including bilirubin infant jaundice, cosmetics applications and in the evaluation of the color of hair or teeth, and other applications. The Color Index is measured and calculated from the reflectance spectrum of any skin (or teeth, hair or material substance) by a two step process. The first step is the weighting of the visible spectra with a unique set of weighting factors which calculate a sample's reflectance spectrum's contribution to the appearance of four color components independent of the illuminating condition. The second step places the sample's reflectance spectrum's contribution to the appearance of the four color components in opponency to each other and calculates the Color Index providing attributes representative of correlates of lightness-darkness (L, also referred to as lightness), redness-greenness (M) and yellowness-blueness (N).

The invention claimed is:  
     
         1 . A method for evaluating color of a sample using a Color Measurement System with a Color Index, said method comprising: 
 measuring said sample's reflectance spectrum;    weighting of said reflectance spectrum with weighting factors corresponding to four color components that form two opponent pairs of color components; and    determining individual contributions corresponding to each of said four color components and calculating said Color Index using said individual contributions and respective contributions to each of a respective one of said four color components by a perfect diffuser, said determining comprising: 
 summing said sample's reflectance spectrum's contribution to the appearance of each of a respective one of said four color components at a plurality of wavelengths into said individual contributions corresponding to each of said four color components.