A silhouette is a shape without detail. Silhouettes are often very effective against an inspiring sky. The trouble is, whilst we can often get interesting silhouettes, we don’t necessarily get them against the sky of our choice. In such cases, using Photoshop, we can combine a silhouette with a sky of our choice.
1. Open both the images – the silhouette as well as the sky – side by side in Photoshop. Ensure that both the images are of the same size and resolution*, and in the same color space. If the Layers palette is not open, press the F7 key to open it. If the silhouette isn’t a perfect silhouette (meaning that you can see details in it), use Levels or Curves to increase the contrast till all detail is lost.
* If the images are not the same size and resolution, it’s easy to enlarge the smaller image using Ctrl + T (Free Transform). But to keep it simple, for this article we’ll take both the images of the same size and resolution.
Note: If your silhouette image has some color/tonality in the sky, it will cause a color shift/ghost image when you blend in the other image. If that be the case, select the sky using whatever method you are comfortable with, and press Delete on the keyboard. You may have to refine the selection edges.
2. Activate the silhouette image and with the Move Tool (V), drag it on to the sky image. After you have started dragging, press and hold the Shift key to center the image if required.
Go to the Blending mode option in the Layers palette (click the tiny arrow where it says Normal) and select Multiply.
The two images should merge well. If further editing is required (controlling contrast, saturation, sharpness etc.), you can do the same.