Sobel filetered image from source image.  Tangent Flow Map(TFM) with Source image and Sobel filetered image.  Alpha value of Tangent Flow Map(TFM) calculated by sobel filter 
Sobel filetered image from source image.

Tangent Flow Map(TFM) with Source image and Sobel filetered image.

Alpha value of Tangent Flow Map(TFM) calculated by sobel filter
