This is my adaptation of this PS tute. I emailed over a year ago and asked permission, but never heard back from them. As my method has some twists (no pun intended) on the method, I figured it wasn't ripping, since I use slightly different methods than the author and mine takes the further step of making the "wraps" three dimensional.
Okay, start out with a fairly large canvas. I am using my standard 600x600. You can always shrink this later.
Select the Paths Tool and make some paths like the one below. (If you don't know how to use paths, look at fencepost's Creating and Using Paths Tutorial.) It is helpful as you drag out the control node to shape the curve, to hold down shift, once you have started to drag, so you get "equal" handles on either side of the node. You want a fairly shallow curve.
Once you have the path, name it "upper", duplicate it, and name the duplicate "lower". Move it in the paths dialog so that it is below the one labeled "upper". Make sure the eyes for both paths are clicked on so that you can see them.
Now we are gonna spin the duplicate around. (In case you don't know, most of the transform tools, such as rotate, scale, etc., have an option to have them work not just on the layer or a selection, but on a path as well. Look at the icons in the options window that opens up in the bottom of the toolbox when you select the tool. For the Rotate Tool, next to the word "Affect" in the options dialog at the bottom of the toolbox window, will be three icons. Hover your mouse over the third one. A tooltip should come up that says "Transform Path". That is the one you want. Use it to rotate the duplicate path 180 degrees.
Now you have something like the image below. Yours may look different if you drew your path in a different location, or used a different sized canvas.
So, pick the Move Tool and click the same icon down in the options dialog, and move your path into position so it looks like the one below.
Finally, go back into the Path Tool and change some of the node positioning/curvature to get a nice looking barbed wire section.
Okay, now we start making some barbed wire.
Create a new transparent layer and either bucket fill it with black, or have it pick the default black foreground color when you make the new layer.
Switch your colors so that your foreground color is white. You can either click in the toolbox to switch, or press the "x" key.
Go to the paths dialog and pick your "upper" path. Right click on it and then click on Stroke Path. I am using an 8 pixel stroke, but you may want to use one that is bigger or smaller.
Do the same thing to the "lower" path.
So now you have two curved white lines intersecting on a black background.
Do Filters>Blur>Gaussian Blur. I used a value of 10 pixels.
Now do Filters>Light Effects>Lighting Effects.
In the Light tab, change the type of light to directional and, using the handle in the preview window, angle the light as shown in the preview window. In the same tab, click on where it says "Light 1" and add a second light, also directional. Angle it the opposite way. The screenshot below shows both lights at once, but the actual dialog will only allow you to work with and view one light at a time.
Now go to the tab that says "Bump Mapping" and check the enable box. The bump map source should be the layer you are working on. Set the mode to sinusoidal and the amount to .05.
Run the filter.
You get this:
Kinda raggedy lookin', huh?
We are gonna fix that right now. There are probably other ways to do this, but I like this method, since it uses the actual path used to create the lines.
Right click on the layer you just ran the filter on and then click on "Add Layer Mask". A dialog will pop up. Pick "Black (Full Transparency)" and click okay.
Your layer will seem to go bye bye. Don't worry, it is still there, it is just covered up by the mask.
Now we are gonna make the barbed wire come back. If you notice, there is now a black square next to the image thumbnail in your layers dialog. Click on it, it will get a white border.
This means that the mask, not the image is selected. Very important to make sure you do this. If you have the image selected, then the next step will happen to the image and not to the layer mask.
Make sure your foreground color is set to white. Go to your Paths Tab and pick the "upper" path. Stroke the path just like you did before, only this time, use a width value of 10. Turn the eyes on your paths off.
You get an image something like the one shown further down. You painted in white on the black mask. White "reveals" what is in the layer and black "erases". The information isn't really gone, its just covered up by the mask. Now, if your wire is looking a bit thin, you might try stroking with a wider brush.
Lets soften up the cut the mask makes a bit. With the mask selected (white border around it), do Filters>Blur>Gaussian Blur with a value of 3 pixels. If you look at the preview, you see the mask, white lines on a black background. Blurring the mask has the same effect as feathering a selection, only you get to actually see how much it is feathered. Right click on the Layer and then click on "Mask to Selection".
Now click on the image thumbnail in the layers dialog. It will get a white border. Whatever you do now, happens to the image. The Image, not the mask, is what is now selected.
Do Filters>Blur>Gaussian Blur with a value of 2-3 pixels. This will soften up the harsh jaggies created by the Lighting Filter.
Right click on the layer and then click on "Apply Layer Mask". This will permanently erase the black area around the wire.
Now lets create the barbs. This is basic painting stuff.
Set your foreground color to black, if it isn't already.
Now we are gonna make a custom brush to make the barbs with.
In the Brushes dialog, click the "New Brush" icon. This opens the Brush Editor window. Make a brush with the settings shown. (you can vary these, if need be, if you used a different sized canvas).
Create a new white layer and lower the opacity down to where you can see the wire layer underneath.
With the brush you just made, draw the barb as shown. To get the straight lines, click once at the starting point and then hold down
Turn the opacity back up on the white layer. Use the rectangular select tool to select an area around your brush. Do Edit>Copy, then Edit>Paste as New.
In the new window that comes up with your brush, do Image>Mode>Grayscale. Do Select>Select by Color on the white area of the image, then do Select>Invert. Do Image>Crop. Do Script>Fu>Selection>Selection to Brush. Name and describe your brush appropriately in the dialog that comes up and save it. It will now be the default brush.
Make a new transparent layer above the wire layer. With your new brush, brush the barbs on this layer in the appropriate locations.
Duplicate this barb layer and turn the duplicate off by clicking the eye symbol.
Make a new white layer underneath the barb layer that is still "on". Merge the barb layer down onto the white layer. Do Layer>Colors>Invert. You now have white barbs on a black layer.
Run Filters>Light Effects>Lighting Effects on this layer with the same setup you did before on the wire layer.
On the layer above, the one with the black barbs on transparency, do Layer>Transparency>Alpha to selection. Do Select>Grow and grow the selection by one pixel. Do Select>Invert.
Go to the barb layer you just ran the Lighting Effects filter on. Do Edit>Cut. Now you have your nice metallic barbs on a layer above the wire.
I screwed up when I made my brush and didn't get it "black" enough (had fade out checked in the brush options dialog and didn't notice), so some of the wire shows through my barbs. I duplicated the barb layer we just did to compensate for this, then merged down.
Now we are gonna soften up the effects of the Lighting Filter. On the barb layer you just did, do Layer>Transparency>Alpha to Selection. Then do Filters>Blur>Gaussian Blur with a value of three.
Leave the selection active, we need it for the next step.
Notice how the barbs are kinda flat looking. They are this way in the original PS tute, as well. We will fix this next and make the barbs look three dimensional, like they actually wrap around the wires in the wire layer.
Make a new transparent layer above the wire layer, but below the barb layer. Turn on Quick Mask. To do this, you can either click the little "red square icon" in the lower left corner of the canvas (clicking toggles it on and off), or do Select>Toggle Quick Mask, or press
Now, when you paint on the canvas in black, you will be painting on the Quick Mask and it will show up as red. Paint your Quick Mask to look like below.
Toggle the Quick Mask off to make it back into a selection. Now you have just the middle of one barb selected.
Pick the Gradient tool. Configure the options like below. Draw a gradient in the selection as in the next picture. (I have a white background behind, to show things better, this is actually done on a TRANSPARENT layer, not a white layer) Notice how the gradient is done at the same angle as the wrap wires. Leave the selection active.
Now you have this weird little gradient behind one of the wraps. Turn on your wrap layer and lower the opacity so you can see the gradient behind it.
Do Edit>Copy and Edit>Paste. Use the Move Tool to drag the copied gradient so it lines up underneath another wrap. Repeat this step for all the wraps, leaving the selection active until you are done.
Once you have gradients behind all the wraps, do Select>None.
So you have a layer with these funny little gradients on a transparent background.
Do Filters>Blur>Gaussian Blur with a value of 15 on this layer. Duplicate the layer and merge the copy down onto the original.
Select your barb layer. Do Filters>Map>Bump Map, using the gradient layer you just made as a bump map source. Make sure you use the Sinusoidal map, anything else will make the barbs bend kinda funny. Adjust the Azimuth, Depth, and Elevation settings in keeping with how the light hits the wire layer.
Turn off the gradient layer. If you haven't turned the opacity back up on your barb layer, do so now. Turn on your wire layer if need be. You should have this:
Basically, you are done. From here you can put it on a different background, add some blood drips, maybe do some rust with the Scott Effect(that's what I did in the version below). You can also give the barbs just a kiss of Filters>Distorts>Iwarp to make the barbs look slightly bent and random.