Mono post processing for particular effect?

In a local department store there is a very large, almost cartoon like image in black, grey and white of stonehenge. Its not mine so forgive me for not showing the image!

I have similar images of the stones and tried playing with them but simply have no idea how this simple but effective three tone monochrome was produced. The grey is all one single tone.

Anyone got an idea?

I've managed a very odd mono representation by playing with curves, but its not what I had hoped to achieve. I'm very happy to post up my colour starter image if anyone fancies playing.

Try converting the image to B&W and then use the filter/layer adjustment in PS called "Posterize" - posterize will group the entire range of tonal values into bins, the number of which you can specify. So, if you want 3 tones, all of the pixels in the image will become black, gray or white depending upon their place in the histogram.

For a completely non-destructive PS workflow, use a Black and White adjustment layer to make the conversion and then stack a Posterize adjustment layer on top of that. Then, you can tweak the B&W adjustment layer to move the grayscale values around and get the look you want in the final, posterized version.

kirk

Kirk,

That sounds exactly what the Doctor ordered. Thanks a million.

Very difficult to guess without seeing the image, or at least an example of something similar.

In PS, with a curves layer there is an option to draw a curve (pencil icon I believe). Try drawing a curve that starts in the bottom left, goes up at a steep angle to whatever gray level you want, is flat across most of the histogram and then goes up to 255,255 quickly and steeply towards the end of the histogram.

You will have to play around a little bit to get it to look like you want, but that will make all the mid tones the same shade of gray.

doidinho,

Thanks for your input as well, its much appreciated. Heres my first attempt, its not quite what I've got in mind but now you have both given me your ideas I can play with it more.