Step 1) Opening the image

Open up an image that has a clearly-defined outline that differentiates elements within the photo. I have included a file in the final source final download to use if you do not have one.

Step 2) Selecting the Adjustment

Go to Image>Adjustments>Threshhold

Step 3) Using threshold to fix the image

Drag the arrow so that the subjects in the photo and other areas we want to be visible are black. For the helicopter photo, place the arrow between the two areas of pixels. For this example, I set it to 90. Press OK.

Step 4) Fixing the background layer

We need to make the Background layer a normal layer in order to remove the white pixels. Double-click the Background layer and click OK to name it its default name, Layer 0.

Step 5) Removing the White Pixels

There are many ways to select the white pixels, but let’s just use the simple Magic Wand tool.

Set the Tolerance to 0 and make sure Contiguous is unchecked. This will ensure that the white pixels that are not adjacent to, or contiguous to, the white area of pixels that we click will still be selected. Click somewhere in the white pixels and press Backspace to delete them

Step 6) Creating a new layer

Next, click on the New Layer icon on the bottom of the Layers palette to create a new layer. Click-and-drag this layer so it’s below Layer 0.

Step 7) Setting up the gradient tool

With the Marquee Selection tool, click somewhere on the image to de-select the pixels, if they are still selected. Select the Gradient tool. With Layer 1 selected in the Layers palette, and the Gradient tool selected, double-click on the Foreground Color selector near the bottom of the toolbar. Set it to White. Double-click the Background Color selector and set it to an orange hue. I set mine to #ffa800. This sets the color of each side of the gradient.

Step 8) Adding a gradient to the image

Click-and-drag from the top of the image to about a fourth from the bottom. Press Shift to maintain a straight vertical line.