Add a new dynamic to your portraits with a silhouette effect using the Levels and Gradient Map adjustments
Open an image of a person and make a selection around them using either the Magic Wand tool (to select the background) or the Quick Selection tool (to select the person), whichever one is easiest. Feather the selection by 1px by going to the Select menu, down to Modify, and then to Feather.
When you’re happy with the selection, apply a new Gradient Map adjustment (Layer>New Adjustment Layer). Chances are the person will turn black and white. The selection should apply itself to the mask of the adjustment.
Open up the Gradient Editor menu by clicking on the adjustment’s layer. Choose a colour to use for the gradient. We went for blue, but make sure that the two swatches of the gradient are the same hue. One needs to be lighter than the other.
Cmd/Ctrl-click on the Gradient Map’s mask to reactivate the selection of the person. Add the Levels adjustment layer and reduce the Output Levels under the main graph in the adjustment. The image should darken. You can darken the midtones and shadows for an even more dramatic silhouette.
Click on the Background layer and press Cmd/Ctrl+J to make a copy of it. Cmd/Ctrl-click on one of the adjustment’s mask once more to reactivate the selection, and then go to Select>Inverse. On the duplicate layer, apply a layer mask.
Double-click on the duplicate background layer to open Layer Styles. Add the Gradient Overlay option and set its Style to Radial, Scale to 150% and colour from white to the same blue used for the Gradient Map adjustment.
Use the Brush tool on the Levels adjustment’s mask to bring through parts of the image, such as eyes.