I started out with a cap of the scene; after cropping and resizing it, I have the base I'm going to use.
Duplicate the base layer, and set to screen. Flatten the image.
Duplicate and set to Overlay at 100:
Duplicate the background again (this should be the image you get after merging the Screen layer and original base), bring it to the top, and set to Multiply, at 40.
Now for the actual colouring. I flood-filled a layer with a pale blue:
Set that to 'Divide' at 100. (PS and PSP users, this blend mode won't be available; please follow the steps at the end of the tutorial to create the same effect.) The image now looks like this:
I filled a new layer with the same blue, and set it to Burn at 60 (PS users, I'd assume 'Colour Burn' and not 'Linear Burn').
Now, I selected the entire image, copied visible layers (Edit >> Copy Visible in GIMP), and pasted onto a new layer. I desaturated it (Layer >> Colours >> Desaturate), to get this:
Duplicate that twice, and set to screen. This is the result:
Ugly like all hell, but this is an intermediate step.
Now, merge those layers (the black-and-white ones only!). With a medium-sized round brush in black, fill in the Baudelaires' silhouettes. (This didn't really need this many steps, but it's the cleanest way to get the edges right.) Select, and cut.
My layer looked something like this:
On a new layer, flood-fill with pale blue. Add a layer mask (right-click, and 'Add Layer Mask'), and paste in your silhouette layer. Set this one to Burn at 40. The image now looks like this:
Create a new layer, and flood-fill with black. Add a layer mask, paste in your silhouettes, and INVERT the colours. (Layer >> Colours >> Invert). Set this layer to Colour at 50.
Flatten the image. Duplicate and set to Soft Light at 30:
For a minor colour tweak, I flood-filled a new layer on top with this dark blue:
That was set to 'Difference' at 20, to produce my final result.
Work-around for Photoshop/PSP users
At the step of the tutorial where I suggested a blue layer on divide, stop. Copy merged, and paste into a new layer; now, invert the colours.
After that's done, flood-fill a new layer with the pale blue, and set to Burn (Colour, not Linear) on 100:
Merge, and invert the colours again:
This should solve the problem of PS/PSP not having the 'divide' blend mode.
This is a guide. Please don't copy this icon exactly, although you're more than welcome to use it with credit. (It is not, however, a finished icon.) Invent your own spin on things.
Previous tutorials can be found in the community memories.