In this paper, we propose a mouth extraction method based on an integrated combination of color difference features, texture information characterized by the CFI (Co-occurrence Frequency Image) feature of the pixels, and the topological features of the extracted mouth region. The negative known that the ill effects caused by the presence of a mustache can be successfully suppressed by using the proposed method.
Mouth extraction is performed by using the CIE L*a*b* color space and its behavior was investigated. The system brings L* of CIE L*a*b* to the same value in all the pixels. The presence of a mustache and/or wrinkles around the mouth affects the extraction. Mustache color and skin color are closer to the gray scale than mouth color. If the system brings L* to the same value in all the pixels, mouth extraction would be unaffected by the presence of a shadow or mustache. Moreover, the weight of a* of CIE L*a*b* could provide a strong affect for emphasizing the difference between mouth and the surrounding skin region.
In the proposed method, the input image is binarized by referring to the CFI of the converted image. When the boundary between the mouth and the skin is not clear, CFI, the frequency of occurrence of a pixel pair of the image, is referred to detect such a boundary, because the frequency at the boundary is always low. We present the experimental results obtained and show that proposed method can be successfully used for mouth extraction.
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