Image Interpolation Using Coons Surface Patch with Shape Control Parameters

Piecewise bicubic Coons surface patch with adjustable parameters to modify the length and direction of tangent vector at some control points is constructed for a digital image. Boundary curves are first adjusted to fit the image edges. Then the U-V tangent vectors at interior control points and twist vectors at corner points of the surface patch are adjusted to fit the whole image. Such an approach can counteract the smoothing effect of traditional methods greatly and keep the image edges still sharp and smooth.