This is a simple but effective way to create a ‘draped cloth’ effect that can be used as the base texture of (for example) capes or curtains. I’m afraid that this one is specific to the Gimp graphics program, although possibly other programs will have similar features.

Start with an empty picture, at a large size such as 512 x 512, or even 1024 x 1024. I do this with all my textures. Starting large and scaling down usually works well, and sometimes actually improves things by removing or hiding small glitches, whereas it is well-nigh impossible to get good results by starting small and scaling up.

Find the Solid Noise option, under the Filters/Render/Clouds menu.

Set the options so that the X size is set to the maximum, or somewhere near it, and the Y size is set to the minimum, 0.0. You can try experimenting with different values, but you need to be aware that setting the Y size to anything other than the minimum can make it more difficult to create a seamless texture.

You should already see the drape effect.

If you want to increase or decrease the ‘depth’ of the effect, use the Brightness and Contrast — lowering the Contrast will make the effect shallower, increasing the depth (especially in conjunction with decreasing the Brightness) will make the effect deeper.

I would now colorise the texture. Select the Colorise option. Adjust the Hue slider to get the colour you want. Play with the other two sliders to tweak the result.

At this point, the drape will tile horizontally, but probably not vertically. There is a fairly easy way to fix this.

Start by selecting the top half of the image (you don’t have to be exact, but make sure that the top edge is at 0). Feather this fairly drastically, possibly to something like 50 pixels, then copy it. Paste it back in, flip it vertically, then move it down to the bottom, being careful not to move it horizontally.

If you find that the texture does not tile horizontally, you can apply a similar technique to the left and right sides of the texture.

The end result should be tileable. This technique of copying and pasting the top/bottom (and equally the left/right) halves of an image can often be used to make an image tileable if it has right/left or top/bottom symmetry.

Here is an example of the final result:

Drape texture