In this Photoshop tutorial the High Pass filter has been used to sharpen images, with help from a blend mode
This is a quick method to sharpen an image and requires a single duplicate layer.
The High Pass filter detects all the edges in an image and blocks out everything else. By blending the filter with the original layer, the end results are bold and lively.
If your image has layers, flatten the file and Save As a new document before continuing. First duplicate the Background layer of the image by dragging it to the Create A New Layer button. This will be the layer for the High Pass filter.
Go to Filter>Other and select the option High Pass. This opens a separate menu where your image will now look gray. Adjust the Radius slider until you see the edges of each subject come through. This amount will vary depending on your image’s size, but look to keep the effect subtle. Hit OK when done.
To blend the two layers together and apply this filter as a sharpening effect, set layer’s mode to Hard Light. The blend mode hides the gray areas in the image and increases the contrast where the High Pass highlights lie.