Assessing human skin color from uncalibrated images

Abstract

Images of a scene captured with multiple cameras will have different color values because of variations in color rendering across devices. We present a method to accurately retrieve color information from uncalibrated images taken under uncontrolled lighting conditions with an unknown device and no access to raw data, but with a limited number of reference colors in the scene. The method is used to assess skin tones. A subject is imaged with a calibration target. The target is extracted and its color values are used to compute a color correction transform that is applied to the entire image. We establish that the best mapping is done using a target consisting of skin colored patches representing the whole range of human skin colors. We show that color information extracted from images is well correlated with color data derived from spectral measurements of skin. We also show that skin color can be consistently measured across cameras with different color rendering and resolutions ranging from 0.1 to 4.0 megapixels.

Color match

“…Our studies showed that our system gives a comparable distribution of predictions as that found between two cosmetic experts under different lighting conditions and different consumer imaging devices and different cosmetic product lines [9,10]. The system can be configured to plug in any expert opinion that the consumers like, or the brand wants, or the public respects, etc.…”

“…This matrix fixes the alteration of the image and maps it closer to the "true color". This means that pixels from the face can be relied on to accurately represent the subject's skin color [9,10].…”

Improved Skin Lesion Diagnostics for General Practice by Computer-Aided Diagnostics

“…A different method to assess skin tones and retrieve color information from uncalibrated images consists on imaging a skin region with a calibration target and extracting its color values to compute a color correction transform [52].…”

Mobile cosmetics advisor: an imaging based mobile service

“…We have addressed these issues in great detail in [10,11], here we present a summary of the service's ability to color correct facial skin from un-calibrated images.…”

“…We determined the correlation between imaged face color values and spectrally derived values to be high. The details of this analysis are published elsewhere [11].…”