Quick photo to vector transform
In this tutorial I will show you how to quickly transform photo to vector looking-like-image using photoshop and illustrator tools.
transformation
After you decided what image to transform to vector (I found Olga Kurylenko 
)
1 ) Open it in PS, and duplicate layer.
Apply Desaturate and Sharpen to duplicated ( second ) layer and set it to 50% opacity.
desaturate and sharpen on duplicated layer
2. Merge first and second layer ( background copy + background ).
Select layer after Merge, and Open it in Illustrator.
( just select all ctrl + a in PS, and ctrl + c to copy, then paste it with ctrl + v in Illustrator, OR, drag and drop that layer from Photoshop into Illustrator )
3. After opened in Illustrator
Go to Object >> Live Trace >> Tracing Options
live trace
Check Preview option, and set Treshold to 30.
Click Trace.
4. Copy Traced layer from Illustrator into Photoshop.
Set Opacity in Photoshop to 20% to traced layer.
5. Go into Illustrator and UNDO tracing you did before.
Then go again to Go to Object >> Live Trace >> Tracing Options
But this time, change Treshold to 60.
Click Trace.
6. Copy Traced layer from Illustrator into Photoshop.
Set Opacity in Photoshop to 20% to traced layer.
copied trace
7. Repeat that few times, increasing Treshold
( here is increased by 30 every time, you can try different if you like, also you can experiment with opacity in photoshop, here is used 20% )
repeating
8. After you are satisfied with results, you can Merge it all and Desaturate, then paint it ( new layer with multiply )
Final results:
black and white
and
color
Cheers!