Patent ID: 8182425

Claim:
A method for measuring skin hydration comprising: a) acquiring a first digital image of skin under parallel polarization conditions filtered at a first wavelength λ 1PP of from about 700 to about 900 nm; b) acquiring a second digital image of skin under orthogonal polarization conditions filtered at the first wavelength λ 1XP of from about 700 to about 900 nm; c) acquiring a third digital image of skin under parallel polarization conditions filtered at a second wavelength λ 2PP of from about 900 to about 1000 nm; d) acquiring a fourth digital image of skin under orthogonal polarization conditions filtered at the second wavelength λ 2XP of from about 900 to about 1000 nm; e) using a processing means, generating reflectance values for each of the four digital images; and f) using a processing means, applying the reflectance values to the following Equation I: - log ( ( reflectance ⁢ ⁢ at ⁢ ⁢ λ 2 ⁢ PP - α ⁢ ⁢ reflectance ⁢ ⁢ at ⁢ ⁢ λ 2 ⁢ XP ) ( reflectance ⁢ ⁢ at ⁢ ⁢ λ 1 ⁢ PP - α ⁢ ⁢ reflectance ⁢ ⁢ at ⁢ ⁢ λ 1 ⁢ XP ) wherein α is a parameter used to adjust to account for the amount of diffused reflected light in said parallel polarized images and is between about 0.2 and about 0.4, such that said processing means generates a fifth digital image of the skin using the output of Equation I.