Here's a quick tip for trying to achieve that "PS smudge and/or scatter effect." I understand it's not exact, but it's a good way to approximate the results. I've provided 3 GIMP animated brushes (2 that I made and the default GIMP vine brush which was converted to grayscale) for you to experiment with. Use them and abuse them, but also try making your own. Texture brushes with various shades of gray and black work best. Most brushes are probably too large to work with so I recommend shrinking them to fit the canvas size.

Download and extract them to your GIMP brushes folder and then refresh your brushes.

INSTRUCTIONS FOR USE

I generally start out by using the clone tool to copy portions of the image to other locations. Here's a general description of using the clone tool; however, I recommend you do some experimentation with the various settings to get something you like.

* Grab one of your animated brushes and double-click the clone tool button (looks like a rubber stamp) to open the clone tool options window.
* I suggest you experiment with the various settings, but here's some that I work with: hard edge setting clicked on and an opacity of about 15% or so. When you use the hard edge, you don't need too much on the opacity. However, once you turn off hard edge, you'll see a significant drop in how much of the cloned area shows up. Also, experiment with aligned/non-aligned settings. Aligned will move the clone point relative to the current postion of your mouse pointer. Non-aligned will continue to clone from the area you originally selected.
* To actually use the clone tool, hold down the ctrl key and you'll see the mouse pointer changes to a cross-hair. When you're over the area you want to clone, click with the mouse button while holding down the ctrl key. Now, every time you click that part of the image will be added. If you drag your brush rather than click not only will the portion of the image you clicked on become visible, but so will the surrounding portions. By continuously moving your cursor over areas you've already "cloned or painted", it will give it a smudged appearance.

I also like to use the regular paint brush tool to either supplement the clone tool or in lieu of the clone tool. Here's how:

* Select one of the brushes, double-click the brush button to open the brush options window and reduce the opacity/spacing of the brush to taste.
* Now, on the layer you want to smudge/scatter, Ctrl-Click the render (this will pick a color from the image and make it the foreground color).
* Now, brush away(either by individual clicking or dragging your mouse).
* Then, when your ready to change the color, Ctrl-Click on another color of the render.

The various layers of the brushes will create different textures. Also, try sharpening the layer to give it a bit of an edge. The GIMP smudge tool does not work with animated brushes. It only sees the first brush layer.

Hope this helps!

*Comments are certainly not required, but it's always nice to get feedback!*

Art