Misunderstood Photoshop: The Gradient Map Tool
In this series, Helen Bradley discusses some handy Photoshop tools that are often overlooked or misunderstood, either because they’re hidden away or because their use isn’t immediately apparent. Yet these tools provide smart and useful ways to perform various tasks in Photoshop, so they’re worthy of adding to your Photoshop skill list.
In this sixth part of the series, we consider the Gradient Map tool, which is useful for converting color images to black-and-white and for colorizing grayscale or color images. It’s a handy and fun creative tool for photo editing.
About the Gradient Map
Photoshop offers many ways to convert an image from color to black-and-white. Unlike the other tools, however, the Gradient Map gives you a lot of control over how your image is converted. You also can use the Gradient Map to colorize a black-and-white image or to change the colors in a color image. This all-around tool’s interesting features can take you to new heights in your photo editing.
Gradient mapping in Photoshop is applied using an adjustment layer. The Gradient Map adjustment layer alters the image by applying a gradient map to the image. Unlike a gradient fill, which fills an area by using a linear or radiant blend of colors, the gradient map applies the gradient by using the lightness and darkness values in the image as a map for how the gradient colors are applied.
The best way to see how the Gradient Map tool works is to try it out. Here’s how to use it to turn a color image into a black-and-white image:
- Open a color image in Photoshop. Display the Layers palette if it isn’t already visible (Window > Layers).
- Set the foreground color to black and the background color to white.
- Choose Layer > New Adjustment Layer > Gradient Map to add a new
Gradient Map adjustment layer. Click OK to select the current settings as those
for the layer. When the Gradient Map dialog appears, notice that the gradient
ranges from the foreground color to the background color—by default, it
uses the current foreground and background colors. Notice too that the color
photograph is now converted to black-and-white (see Figure 1).
Figure 1 The Gradient Map tool uses the current foreground and background colors and applies a gradient across the image. Here, because the foreground and background colors are black-and-white, the image is converted to grayscale.
- To change the gradient effect, click the gradient in the dialog to open the Gradient Editor. On the left side of the gradient is the current foreground color; the color is mapped to the darker areas of the image. On the right is the background color, which is mapped to the lighter areas of the image. The middle color in the gradient is mapped to the image midtones. To change how the colors are mapped, drag one of the indicators (called a color stop) under the gradient to change the gradient.
- The small diamond between two color pointers is the color
midpoint; it can be dragged to the left or right to alter the midpoint
between the colors in the adjacent color stops (see Figure 2). When you achieve
a result that looks interesting, click OK and OK again to apply the newly edited
gradient map to the image.
Figure 2 Using the Gradient Editor, you can alter the gradient by dragging the color stops and the color midpoint indicators under the gradient. As you do this, you can preview the effect of the changes on the image.