Is there a way to algorithmically create (no painting or brushes) Nebulae / Wispy Clouds effects in Photoshop. Random clouds and Difference Clouds filters can certainly create interesting patterns, but they are miles away from authentically looking clouds or nebulae. On the other hand several fractal generators can do the trick - and XenoDream and Apohysis in particular can create photo-realistic nebulae and clouds, but doing it straight in Photoshop would be a good skill to have. Any ideas?