When you are sharpening portraits, it is generally a good idea to apply the effect only where it is needed and not globally. There are several ways to selectively sharpen an image, but this method gives you fine control over the location of the effect and produces a naturally sharp look that’s free from unsightly halos.
Step 1
Copy your background layer twice by pressing Ctrl+J (that’s Command+J on a Mac). Highlight both of these new Layers and click on the Create a new group icon at the bottom of the Layers Panel – that’s the icon that looks like a folder.
In Photoshop CC, clicking that New Group icon will move the two selected Layers into a new Group. If you’re on an older version of Photoshop, you’ll need to drag the two Layers into the new Group. Rename the Group to Sharpen for easy identification later.
Step 2
Select the Group you just created to select it. Next, change the Blending Mode by clicking on where it says Normal in the Layers Panel. From the dropdown menu, select Overlay. Then select the top layer in the group and change the Blending Mode to Vivid Light.
Step 3
With the top Layer still selected, invert the layer by tapping Ctrl+I(or Command+I on a Mac). The image in the Preview Window will return to its original look.
Step 4
Now you can apply the sharpening by adding a Surface Blur to the top Layer. With the top layer in the group highlighted select Filter→Blur→Surface Blur. The values will depend on the size of your image, but start with a Radius of 10 and a Threshold of 10. Examine the preview and tweak the values to eliminate halos.
Step 5
Now you have sharpened the image across the board, it’s time to apply it selectively. Do that by selecting the Sharpen group and then hitting the Add layer mask icon in the Layers Panel.Wherever the Layer Mask is white, the sharpening will be visible. Wherever the Layer Mask is black, the sharpening will be invisible.
Step 6
With the Layer Mask selected, Hit Ctrl+I (or Command+I on a Mac) to invert the colours, turning the white Layer Mask black.This will hide the sharpening effect. Now, with a soft, white brush (B), paint over the areas of the image you want to sharpen. Keep your brush small and focus on details such as the eyes, eyebrows, lips and hair. Avoid sharpening skin or any areas that are not in sharp focus already.
As you work, get into the habit of toggling the visibility of the Group on and off by clicking the eye icon next to the Group’s thumbnail in the Layers Panel. This will help you judge the strength of the effect. If it’s too strong, select the Sharpen Group in the Layers Panel and reduce the Opacity value until it looks right.
You can also press the “\” key to see a Mask Overlay. This will give you a clear idea of where you have painted white and where is still black.