This texture was generated in Filter Forge, a Photoshop plugin that allows you to create your own filters.
This snippet illustrates a method of using gain for bulge and pinch control and much more
Control Description
Control-1 controls the gain in the curve "this affects all examples"
Repeat
this is strictly for example 3 and uses an elevation control
Offset
this controls example 4 and can be used for curve shpes drapes and more
This version is more compicated then its sibling so is being submitted seperatly but it illustrates the way to control the bend point on your gradient
snippet curve gain bulge pinch