Gavin Hoey gave me this idea and I really liked it immediately. It is quick to do but as always you have to choose the original image with some care. The best images for this technique are those with a lot of graphical content; that is the image has big items filling the space. I have found that it also works very well with woodland scenes.
Having chosen a suitable image open this in Photoshop. If using full Photoshop then you can make an action that can speed up the technique.
1. Here is an original photo of a beach hut at Southwold. This image is some 3800 pixels high and for this method to work well you need an image of roughly this size.
2. Duplicate this original and close the original
3. Go to Layer on the Menu bar and click on Duplicate layer. Click OK.
4. Repeat step 3.
5. Click off the Eye icon for the top two layers and activate the Background layer.
6. From the Filter Menu pick Sketch > Bas Relief filter.
7. From the screen grab you will see that the Detail slider is at 13 and the Smoothness is set to 3. These are right for most images. The Light Direction I change for each picture. In this case from Top Left since that is where the sun is shining from. It also means that the bottom right of the final image will be darkened.
8. Here is the result of the Bas Relief filter.
9. On the Layers Palette highlight the next layer up and choose the Blending Mode of Colour from the drop down box at the top of the Palette. This allows some colour to bleed through to the Bas Relief filtered result as seen here.
10. Now from the Layer menu select Merge Down. You now have only two layers.
11. From the Filter Menu pick Artistic > Cut-Out filter.
12. Set this to No. of Levels = 8; Edge Simplicity = 6; and Edge Fidelity = 1. Click OK. See below for a sample.
13. Highlight the top layer and repeat the Cut Out filter with one small but vital change namely Edge Simplicity = 7. The Edge Simplicity will need to be smaller if your original image is smaller than mentioned above in step 1. You may experiment with these settings anyway.
14. From the Blending Options choose Overlay.
15. Now Flatten the result from Layer > Flatten Image.
16. You may wish to do more work on the image such as Lightening or reducing the Saturation according to taste.
Have fun.