You may find it necessary to increase the final image’s sharpness. Because increasing the amount of sharpness in the picture also means increasing the noise levels, you can sharpen only the edges. In a portrait it is important for the eyes to be in focus and sharp, as they are the main points of interest in a face. It is recommended to increase only the eye’s sharpness and to leave untouched areas such as skin, because modifying these parts can lead to unwanted artifacts.

Before you proceed to applying sharpness to your image, you should add a layer that contains a merged copy of the image that you want to sharpen. Add a new layer on top of all the other layers by clicking on the “Create a new Layer” icon which you will find in the layers palette. Rename this layer “Merged Image”.

Press Ctrl+Alt+Shift+E to merge all visible layers on the active layer. Duplicate this layer (click on the layer's thumbnail, holding down the mouse button; drag the mouse cursor to the “Create a new Layer” icon and then release the mouse button). This new layer will automatically be the active layer and be named “Merged Image copy”.

Go to the menu and select Filter > Other > “High Pass...” Select a value of 1.5 pixels and click OK. The next step is to set the blending mode of this layer to Soft “Light”. Next, click on the “Add Layer Mask” icon to add a mask to this same layer.Press the “D” key to make the fore- and white and the background color black and then press “X” to switch both colors.You can now paint with a “soft brush” on your image to mask those areas that you don't want to be sharpened (skin for example).You can also use other sharpening methods, such as “Unsharp Mask” or the “Smart Sharpen” filter.