Here's a quick look at how the Toto heads are done, and no, it's not a Photoshop filter. These are done in Adobe Illustrator with a Wacom Tablet. The style is a ripoff of Richard Linklater's movies Waking Life and A Scanner Darkly.
Here's the jpeg I'm working from, grayed back.
Lines added using Wacom tablet so line weight can be varied.
Base skin tone laid down.
Two layers of shadowing added. Shading is added transparently so the effect is cumulative.
More darkening, using the 'multiply' setting. Some shadows have a blue tint, some have a red tint.
Highlights, eyebrows, lips added.
A red base for the eyes.
The whites of the eyes.
The lighter part of the irises define the pupils
A shadow under the eyelid helps make the eyes appear round.
The hair behind the head is added, with a couple layers of shading.
The hair in front of the head blocked in.
First layer of hair highlights.
A second layer of highlights.
Ascot added, all done.