1. A method comprising: receiving an image of a marker having a known size, the image of the marker having been captured using a device having an image sensor; calibrating a plurality of settings of the device based on the image of the marker; receiving one or more images of a skin region having a plurality of surfaces, the one or more images of the skin region having been captured using the device; and capturing an accurate color of the skin region by: measuring a color of each of the surfaces of the skin region; determining a surface reflectance of the skin region based on the measured surface colors; and determining a surface color variation of the skin region based on the calibrated settings, the measured surface colors, and the surface reflectance of the skin region.