Creating good Black and White images from a color image is a very complex task, there are many many ways to do it in Photoshop alone. I will demonstrate one simple one here that uses a Gradient Map adjustment layer.
This is a very simple technique that is easy to put into an action, start off by opening your color image and make sure your layer window is showing using Window->Layers.
Create a new Gradient Map adjustment layer using Layer->New Adjustment Layer…->Gradient Map… or using the icon on the layers window.
Immediately after creating the Gradient Map layer you will see a window like the one above, this will contain a gradient using your current selected colors, I had black and white selected already. Click on this strip to see the full options window. In the Presets frame choose the 3rd square this will give you a good Black and White.
Once this is done you can change the Smoothness to your liking, some people like 33%, but it really depends from image to image and your personal taste.
Once you are happy with your results choose Ok on both dialogs and you will have a Black and White image as result.
Amusement Park – Brighton, UK
