Improve Focus by Sharpening Images in Photoshop Elements 10
If your images don’t need any contrast, color, and flaw fixing, feel free to jump right into sharpening. Sometimes, images captured by a scanner or a digital camera are a little soft, and it’s not due to any tonal adjustments. Occasionally, you may even want to sharpen a selected area in your image just so that it stands out more.
First, let us say that you can’t really improve the focus of an image after it’s captured. But you can do a pretty good job of faking it. All sharpening tools work by increasing the contrast between adjacent pixels. This increased contrast causes the edges to appear more distinct, thereby giving the illusion that the focus is improved. Remember that you can also use the Sharpen tool for small areas.
Here’s a description of the two sharpening commands:
Unsharp Mask. Found on the Enhance menu in Full Photo Edit or Quick Photo Edit mode, Unsharp Mask (which gets its odd name from a darkroom technique) is the sharpening tool of choice. It gives you several options that enable you to control the amount of sharpening and the width of the areas to be sharpened. Use them to pinpoint your desired sharpening:
Amount. Specify an amount (from 1 to 500 percent) of edge sharpening. The higher the value, the more contrast between pixels around the edges. Start with a value of 100 percent (or less), which usually gives good contrast without appearing overly grainy.
Radius. Specify the width (from 0.1 to 250 pixels) of the edges that the filter will sharpen. The higher the value, the wider the edge. The value you use is largely based on the resolution of your image. Low-resolution images require a smaller radius value. High-resolution images require a higher value.
Be warned that specifying a value that’s too high overemphasizes the edges of your image and makes it appear too contrasty or even goopy around the edges.
A good guideline in selecting a starting radius value is to divide your image’s resolution by 150. For example, if you have a 300 ppi image, set the radius at 2 and then use your eye to adjust from there.
Threshold. Specify the difference in brightness (from 0 to 255) that must be present between adjacent pixels before the edge is sharpened. A lower value sharpens edges with very little contrast difference. Higher values sharpen only when adjacent pixels are very different in contrast. Leave Threshold set at 0 unless your image is very grainy. Setting the value too high can cause unnatural transitions between sharpened and unsharpened areas.
Occasionally, the values you enter for Amount and Radius may sharpen the image effectively but in turn create excess grain, or noise, in your image. You can sometimes reduce this noise by increasing the Threshold value.
Adjust Sharpness. When you’re looking for precision in your image sharpening, Unsharp Mask is one option. The Adjust Sharpness command is the other. This feature enables you to control the amount of sharpening applied to shadow and highlight areas. It also allows you to select from various sharpening algorithms.
Here are the various options you can specify:
Amount and Radius. See the two descriptions in the preceding Unsharp Mask bullet list.
Remove. Choose your sharpening algorithm. Gaussian Blur is the algorithm used for the Unsharp Mask command. Lens Blur detects detail in the image and attempts to respect the details while reducing the nasty halos that can occur with sharpening. Motion Blur tries to sharpen the blurring that occurs when you move the camera (or if your subject doesn’t sit still).
Angle. Specify the direction of motion for the Motion Blur algorithm, described in the preceding bullet.
More Refined. This option runs the algorithm more slowly than the default speed for better accuracy.