There are several techniques in Photoshop that can be used to convert a full colour photograph into black and white. Typically, a Photoshop “newbie” like me in the past will just pull the saturation bar to the minimum to desaturate the colour or choose “Grayscale” in the image mode.. However this kind of conventional method, you tend to lose control over the details and contrast that you wish to preserve in the photo. You will end up with a photo that is flat and “normal”.

For this example, we will be using what is call “Lightness Channel”  technique to convert a colour photograph into a proper black and white photo.

Step 1: First open a full colour photo in photoshop. Go to Image>Mode>Lab Colour. By doing this, you will not see any visual difference now.

Step 2: Go to Channel Palette (a tab menu found in default Layer Palette). The photo is now separated into “Lightness” channel from the colour data in “a” and “b”.

Step 3: Select Lightness Channel and go to Image>Mode>Grayscale. The program will prompt you whether you want to discard the other channels, select “yes”.

Step 4: Right now, you will see that you had converted your photograph into black and white, but that not the end! You need to adjust the tone of the photography. Press Crtl+J to duplicate the layer.

Step 5: Select “Multiply” in the blend mode if  your photograph is too light or “Screen” if it is too dark. Choose the opacity level  to adjust the tone to your preference.

Conclusion: This method will gives you better control on your conversion of photograph to black and white. Try this sometimes when you are free in Photoshop and see what you can come up with.