This tutorial will show you how to instantly convert to high-contrast black and white photos in Photoshop using Gradient Map. There are many ways to convert photos to black and white, but Gradient Maps are one of the best because they are fast, easy to use, and deliver great results. This article will show you how to use Gradient Map and the secret why Gradient Maps give black and white photos such a high-contrast look.
How to convert images to black and white using Gradient Map
So let's compare the results from the Desaturate command with the results we get when using Gradient Map.
Turn off the Desaturated layer by clicking its visibility icon:

Step 1: Reset Photoshop's Foreground and Background colors
Before adding a Gradient Map, make sure that in the toolbar your Foreground and Background colors are set to default, with black for Foreground and white for Background:

The reason is that by default, Gradient Maps uses a gradient based on the current Foreground and Background colors. So if your color is set to something else, click on the icon Reset small above. Or press the letter D (dèault) on the keyboard:

Step 2: Add a Gradient Map adjustment layer
Then, to add a Gradient Map, go back to the panel Layersclick the icon New Fill or Adjustment Layers at the end:

And choose a Gradient Map adjustment layer from the list:

Immediately, we get a much higher contrast black and white image, with darker shadows, brighter highlights, and more detail overall:

Compare the results
Here is a comparison of the results from the Desaturate (left) and Gradient Map (right) commands.
You can easily see how the black and white version of Gradient Map looks much better, despite taking the same amount of time. Higher contrast makes the image pop more, with more detail in the model's face and hair, clearer textures on the sweater, and in the background:

How do Gradient Maps convert images to black and white?
So why are Gradient Maps so effective at creating high-contrast black and white images? There are actually two reasons. The first reason is because of how Gradient Map works: Gradient Map will take the original colors in the image and replace them with colors from a gradient.
In the table Propertieswe will see the gradient that Gradient Map is using. By default, this gradient is based on the Foreground and Background colors, which is why it is necessary to reset them to black and white:

Gradient Maps replace colors based on their brightness. So, since we're using a black to white gradient, the darkest colors in the image will be replaced with black or dark gray. The brightest colors currently are white or light gray. And colors with lightnesses in the middle now have shades of gray from the midtones in the gradient:

Why do Gradient Maps produce high contrast images?
So that's why the image is converted to black and white when adding a Gradient Map. But why do black and white images have such high contrast? Why is the Gradient Map's contrast not only higher than the desaturated version but also higher than the original image? The reason is because of an option available in the Gradient Editor.
Open the Gradient Editor
To open the Gradient Editor, click the gradient in the panel Properties:

Smoothness option
And here in the Gradient Editor, right above the gradient preview bar, there's an option called Smoothness. By default, Smoothness is set to 100%. That means Photoshop is trying to smooth the transitions between different colors, or in this case, different shades of gray in the gradient:

How does smoothness affect contrast?
But this smoothing also increases the contrast in the gradient. It increases the difference between dark and light tones by pushing dark tones towards black and light tones towards white. And this is what gives a higher contrast look to black and white images.
Let's see what happens to the image if we reduce Smoothness to 0%:

The high contrast is lost and the black and white image now looks more like the result from the Desaturate command:

But when increasing Smoothness back to 100%, the higher contrast returns:

Expand and contract shadows and highlights
If you pay attention to the gradient preview bar as you increase and decrease the Smoothness value, you can actually see what's happening to the gradient. Note how the darkest shades on the left and lightest shades on the right extend inward toward the midtones with Smoothness set to 100%:

But when you lower the Smoothness value, those darkest and lightest shades are pushed back toward the edges, brightening the midtones. And at 0 % smoothness we have a more natural transition from black to white:

Leave Smoothness at 0% for the time being and click OK to close the Gradient Editor.
And here is a comparison between the desaturated version (left) and the Gradient Map with Smoothness set to 0% (right). Now that we've eliminated the advantage of the Gradient Map by reducing the smoothness, the two versions look more similar, although the Gradient Map still looks a bit better:

Of course, the purpose of using a Gradient Map is to get that high contrast effect. So, reopen the Gradient Editor and reset Smoothness to 100 %. Then click OK to close it. And now, we'll go back to the high-contrast black and white image:
