The Distort module includes parameters that allow you to easily control the degree of distortion in a warp or morph. You can adjust the Iterations parameter so the distorted source pixels more closely approach the destination spline. Similarly, you can adjust the Range parameter to affect all the pixels in the image, or just those in the immediate region of the warp. Displaying the distortion grid can help you evaluate the effects of your changes.
To create a warp or morph, invisible iteration points are added between the source and destination splines. These iteration points determine how many timesthe pixels between the splines is examined when the calculations are performed. Adjusting the number of iteration points is relevant when the distance between the splines is great; that is, when you are trying to achieve a large warp. With a small iteration number, the warp will not “follow” the destination spline closely. Increasing the number of iterations will result in a more obvious distortion. For smaller warps or morphs, there is no advantage in using a greater number of iterations; it simply increases processing time unnecessarily.
By adjusting the range, you can control the region affected by the distortion. A lower value decreases the region affected by the warp, while a higher one increases it. For example, a value of 100% affects all the pixels in the image, a value of 33% affects one-third of the image, a value of 25% affects one-quarter of it. To restrict the distortion to the area immediately surrounding the vertex, choose a higher region number. To broaden the effect, choose a lower number. This parameter has a smaller effect on processing time than the number of iteration points.
To display the distortion grid:
To adjust the amount the distortion “follows” the destination spline:
To change the size of the region affected:
