I use my Picasa a lot to make any photo/pic black and white (B&W) in a sec. But today I want to edit icons. Unfortunately, Picasa doesn't take icons (.png file). I get back to my Photoshop but I have no idea in making photo black & white. My colleague said it has somethin to do with saturation. Okay, got 1 keyword: saturation. Now the task is how to modify saturation in Photoshop. Came across this article which is helpful. Now I get it!
Below are the 3 steps in making your pic/photo B&W: