Now we'll sharpen the image, but first set the view magnification of the scanned image to 100 percent to get the most accurate preview. To sharpen the image go to Filter/Sharpen/Unsharp Mask and a dialog box appears. This box allows you to adjust the effect of the filter by adjusting the amount, radius and threshold settings. A good starting point is an amount of 500, a radius of 1.2, and a threshold of 2. If those setting don't give good results, you can further refine the Unsharp Mask settings by leaving the amount at 500 and adjusting the radius and threshold. Increase the radius to get more detail in the shadow area (Radius is usually between 1 and 5). Use a low threshold value to effect all shades of grayin the image and a higher value threshold to effect just the dark areas (Threshold is usually between 0 and 7). A higher threshold setting will help eliminate dirt (paper noise) in the light areas but may may cause very thin lines to break up.

The setting for this image was, amount 500, radius 5, and threshold 3.