I do most of my photography in color.  However, there are times I prefer a black-and-white picture over color.  In the past, I  carried both color and black-and-white films. Occasionally, I carried several cameras, each loaded with different types of color and black-and-white films. This allowed me to switch between different types of film and shoot color or black and white pictures. This technique however, added bulk to my equipment. Digital photography has changed all that.  I can now shoot in color and convert images I like to black-and-white. there are several ways to convert a color file into a black-and-white file in Photoshop. Other full featured image editing software offer similar tools for converting color images to black-and-white.

1- You can leave the file in RGB mode and then desaturate the colors, by going to Image - Adjust - Hue/Saturation.  Move the slider to the left.  This control removes as much color as you want.  Then you can go to Image - Color Balance and add a bit of  magenta and some yellow to get the exact tone you want.

2- Change the mode by selecting Image - Mode - Grayscale. this is the quickest way to change the color image into black-and-white. The new black-and-white image however, does not have a wide tonal range.  Although this is the fastest way to create a black-and-white image from a color file, it is not the best way and is my least favorite method.

3- You can take an RGB color file and go to Image - Mode - Lab color. Lab color mode allows you to work in Alpha 1 channels for tonal adjustments. Select Choose Windows -  Show Channels. Go to the A and B channels and delete them. You can drag them to the trash can icon in the layer's palette located at the bottom.  This leaves you with the Alpha 1 channel. You can then use the brightness/contrast control or the level control to add just the tonal range in the image.

4- Use layer - New Adjustment Layer- Channel Mixer.  The channel mixer dialog box to open.  Click on OK. A new dialog box will appear.  Check monochrome.  The image changes into black-and-white.  You can now go into each channel - read, green, and blue and adjust the image. 

The four steps mentioned above are the most common ways of converting color images to black-and-white. There are other ways to do this task such as using third party plug-in filters like The Imaging Factory' convert to BW and Nik Color Efex Pro 2 pictured below.

Nik Color Efex Pro 2

Nik Color Efex Pro 2 plug-in is a very sophisticated program for converting color images to  black-and-white. The program offers dynamic contrast control and tonal enhancer among several other controls for creating superior results quickly and easily.

You no longer need to carry several types of films or cameras to shoot in color and black-and-white. Use your digital camera and shoot in color and convert the shots you like to black-and-white. In the past, a darkroom was necessary for total control over the process of making a quality black-and-white print. Digital darkroom now, does the job much more easier and quicker with better results.