Halid, I wouldn't call myself an 'authority' :-) In fact, I am really far from this, so all I can do is tell you how I did it, and show you the original, so you can judge for yourself the loss of quality.
I have first converted the color image to grayscale, then to color again, and played with the color levels a bit, to get the desired look. You can achieve similar results by playing with duotone, I suppose.
Great results ! You could possible be a good authority to reply to a question I have just posted in the forum section on converting Colour to B&W. Any chance you coould take a quick peek ? Thanks Halid