Digital Light & Color

I had difficulty using Motion Blur to generate to illusion of motion in the splashed foam and water from an ocean wave hitting rocks. Using an amount mask was not productive, but I found that motion blurring the entire image and then cloning back the stationary parts of the image came close to what I wanted. There could well be a much better way to achieve my objectives, and a Reference Manual article on the topic or more extensive notes in Help for Motion Blur might be useful.

Motion Blur is intended to simulate camera motion and not subject motion. Generally subject motion involves only part of the image, so I can see how you were trying to use a mask. You might have better luck with Linear Blur plus a mask or with 1:1 cloning.

Thank you. It was easy with linear blur to generate the effect I sought. I had overlooked linear blur. It might be helpful if it were possible to change the name Motion Blur to Camera Motion Blur, and/or to state in the help that the transformation mimics camera motion and that if motion of the subject is to be simulated, Linear Blur might be a better choice.

I would find it helpful if the first topic in the help for a transformation were a section giving the names of related transformations. Some help sections already mention some or all of the related transforms, but more complete listings, perhaps with a phrase describing them could be generally useful.
For example, beginning the help sections of Blur,
Transforms related to Blur
Camera motion blur;
Subject motion blur;
Gaussion blur; a quick approximation
Precise Gaussion; slow, but blurs only where mask allows