We'll start with our base flag.
|Ray's Boissleau Flag|
And an image of some white material that's been ruffled up.
|Ray sent me this as well.|
Open the base flag in GIMP.
Open our ripple image as a layer.
Make a copy, unless you don't worry about a back up. (For some reason I didn't show you how to do this here. There is an icon at the bottom of the layers window to copy the active layer.)
However you decide to do it next you need to scale this silk layer to fit half of your flag image.
|I had already moved the layer some, I had to move it again.|
Move your ripple layer so that it covers the left hand side of your flag (just how the ripples in the image worked out.)
Set the ripple layer to Multiply.
Then adjust Colors > Levels
As you can see I have adjusted the Input levels, raising Black from 0 to 50 (on the right) and White from 255 to 245 (on the left). This has the effect of brightening the White and darkening the black and grey. In my original correspondence with Ray I had only lowered the White value. I think this looks better.
The first half is done.
|Not too shabby.|
Duplicate this completed ripple layer. (See there's your copy icon.)