Unsupervised lip segmentation under natural conditions

An unsupervised algorithm for speaker´s lip segmentation is presented. A color video sequence of the speaker´s face is acquired, under natural lighting conditions and without any particular make-up. First, a logarithmic color transform is performed from the RGB to HI (hue, intensity) color space and sequence dependant parameters are evaluated. Second, a statistical approach using Markov random field modeling segment the mouth shape using the red hue predominant region and motion in a spatiotemporal neighborhood. Simultaneously, a region of interest (ROI) is automatically extracted. Third, the speaker´s lip shape is extracted from the final hue field with good quality results in this challenging situation