Here’s a tip to get your photos really sharp by using a combination of the Unsharp Mask filter and the High Pass filter using Photoshop.
Here I’m using Photoshop CS5.
Start by opening the photo that you want to sharpen.
Press Ctrl+J to duplicate the background layer
Double click the zoom tool to zoom your image to 100%.
At the top of the screen click Filter.
Click Unsharp Mask.
The Unsharp dialog box appears.
Click and drag the radius slider to about 0.5 as a starting point.
Click and drag the Threshold amount to 2.
Click and slowly drag the amount slider to the right until you see halos on the edges.
Start dragging the Amount slider slowly back to the left until the halos are no longer visible.
At this point the image appears sharper.
Press Ctrl+J to duplicate the sharpened layer.
Just above the ‘layer 1 copy’ click on the downward facing black triangle and select Overlay. At this point the photo appears to have a little too much colour, don’t worry , the next step will put it right.
At the top of the screen click filter.
Click High Pass.
The High Pass filter dialog box appears
Click and drag the Radius slider to 2 as a starting point and increase as necessary.
The Sharpened image: