There are plenty of camouflage textures out there to use, in various colours and resolutions, but sometimes you need a custom camo for a specific area. I'll now show you simple ways to turn any colour into a camo design within gimp.
1. Open gimp, create new image, add the camo layer, paint on the layer in the colour you want to use.
I'll use the entire image and place the textures on opengameart later, at a greater resolution.
let's start with green. Now you want to use some noise
(Filters>noise>RGB Noise). Check correlated noise and uncheck
independent RGB, leave everything else and click Ok.
filters>artistic>cubism tile size should be 2.0 and saturation
should be 3.0. Use the background colour to cover any gaps.
Now choose filters>blur>blur to blur the image.
Open the unsharp mask (filters>enhance>unsharp mask); Just change the amount to something that looks good, I'm using 4.0.
Your camo texture is now done, you may blur it to reduce the pixilation, or use filters>map>make seamless to make a seamless texture.
If you want the digital camo, then after you apply the noise, use GIMPressionist instead of cubism. In GIMPressionist choose cubism, apply it, and update. Orientation tab: directions should be 1, on the size tab, both min and max should be 5. Placement should be even and the color should be "center of brush". On the general tab, choose tillable and update to see the results. You shouldn't need to use the unsharp mask on this image, but you can use "make seamless" to make it tillable.
Kep in mind, this is for simple camo textures, you can change any settings to get better results.