1. A method for approximating a gradient, the gradient defining a nonlinear transition from one color or gray level to another in an image where the rate of transition is determined by the function y&equals;x e where e>1, the method comprising: identifying an error tolerance; selecting a starting point and a set point on a curve defined by the function; defining a linear step from the start point to the set point; calculating a maximum error between the linear step and the curve; if the maximum error is less than or equal to the error tolerance, approximating a portion of the gradient corresponding to the linear step with the linear step, if the maximum error is more than the error tolerance, selecting a new set point on the curve closer to the starting point and repeating the calculating step and error checking steps.