In normal skin HR pulse amplitudes (G channel) were typically 2 ??? 4 times higher than in adjacent PWS skin: e.g. 0.75 and 0.25 PV, respectively.From calibration experiments (unpublished) we have determined that the pixel values of the used digital cameras can be related to light intensities as Y ??? 73 ln(I) + k, where Y is a channel (R, G or B) pixel value, I is the actual light intensity to wh