This paper proposes a remote photoplethysmography measurement technique where human skin color variations are analysed for observing human vital signs including but not limited to average heart rate and variation. Remote monitoring of the vital signs could be useful for non-contact physiological and psychological diagnosis. For this purpose, an off-the-self non-invasive video camera is used. Facial appearance modelling is performed for stabilizing color variations in the selected facial region during the signal acquisition stage. The proposed method offers a novel signal processing approach for extracting the periodic component of the raw color signal for the heart rate and variation estimation. To this end, we have collected a ground truth dataset using a PPG instrument attached to the skin of the subject under observation. Objective performance tests show strong correlation with the ground truth values for the estimated heart rate and variation.