Edge Enhance uses the image intensity gradient to enhance object boundaries.
In summary, the result is calculated from the following expression:
Result = Input * {Fraction + (1 - Fraction) * gradient[F (Input)] }
where Fraction is a number between 0 and 1, and F is either a linear or an arc tangent function.
The enhancement method determines the function F. Currently available choices are "Linear" or "Arc Tangent", where "Linear" is essentially not a function at all. In some cases, the arc tangent method yields better edge enhancement.
Fraction determines the relative contribution of the original image and the gradient image. Increasing Fraction increases the similarity of the Result to the Input image. Valid values are between 0 and 1.