Sharpen with filters

Once you have resampled an image, you need to sharpen it up by using the Unsharp Mask or Smart Shapen Filter to correct any blurring that may have occurred during the resampling process. 

Unsharp Mask Filter

The Unsharp Mask filter is one of several Sharpen Filters available on the Filters dropdown menu.

• Unsharp Mask works by locating pixels that differ in contrast from their surrounding pixels, using a threshold you specify. 
• Unsharp Mask then increases the pixels' contrast by the amount you specify.
• You can also specify the radius of the region to be compared.
• It sounds complicated, but the Unsharp Mask dialog box provides a helpful preview of the resulting image. 
• You can view the changes as you adjust the sliders for each of the parameters.

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Try Unsharp Mask Filter

• Open the image in the document window if it is not already open, and select it if other images are open.
• Click Filter-->Sharpen-->Unsharp Mask to open up the image in the Unsharp Mask dialog box.
• Check the Preview checkbox ito see the effects on the entire image in the Document window.
• Slide the Amount slider to the right to increase the contrast in the edge pixels being sharpened. 
• Slide the Radius slider to the right to increase the number of pixels surrounding edge pixels that affect the sharpening.
• Eventually the image becomes quite distorted
• Slide the Threshold slider to the right.
  • Threshold defines how different the sharpened pixels must be from the surrounding area before they are considered edge pixels and sharpened by the filter.
  • The higher it goes, the softer the effect.
• Use the sliders to choose the effect you like and click OK.
• Save the image with a new name in your working folder.

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Example

Example shows the effects of a large increase in the Amount Slider on the eaglesmall.psd image.

The Preview checkbox is left unchecked so that you can compare the effects of the Unsharp Max filter set (at an Amount of 276%) with the previous versions of the eaglesmall.psd image.

This exaggerated amount of sharpening shows how the Filter works by increasing contrast in areas of the image in which light and dark pixels are next to one another.

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Smart Sharpening Filter Provides additional sharpening controls

Try Smart Sharpening Filter

• Set the sharpening algorithm or control the amount of sharpening that occurs in shadow and highlight areas.
• Zoom the document window to 100% to get an accurate view of the sharpening.
• Click Filter > Sharpen > Smart Sharpen.
• Click the Advanced radio button to display the Sharpen, Shadow, and Highlight tabs for more controls
  
• Controls in the Sharpen tab:
  
  • Amount of sharpening. A higher value increases the contrast between edge pixels, which gives the appearance of greater sharpness.
    
  • Radius sets the number of pixels surrounding the edge pixels affected by the sharpening. The higher the radius value, the wider the edge effects and the more obvious the sharpening.
    
  • Remove determines the sharpening algorithm used to sharpen the image.
    • Gaussian Blur is the method used by the Unsharp Mask filter.
    • Lens Blur detects the edges and detail in an image, and provides finer sharpening of detail and reduced sharpening halos.
    • Motion Blur attempts to reduce the effects of blur due to camera or subject movement. Set the Angle control if you choose Motion Blur.
      
    • Angle Sets the direction of motion for the Motion Blur option of the Remove control.
      
  • More Accurate takes longer, but provides more accurate removal of blurring.
    
• Controls in the Shadow and Highlights Tabs
  • Shadow governs dark areas
  • Highlights governs light areas
  • If the dark or light sharpening halos appear too strong you can reduce them with these controls:
    
    • Fade Amount adjusts the amount of sharpening in the highlights or shadows.
      
    • Tonal Width controls range of tones in the shadows or highlights that are modified.
      • Move the slider to the left or right to decrease or increase the Tonal Width value.
      • Smaller values restrict the adjustments to only the darker regions for shadow correction and only the lighter regions for highlight correction.
    • Radius Controls the size of the area around each pixel that is used to determine whether a pixel is in the shadows or highlights. Moving the slider to the left specifies a smaller area, and moving it to the right specifies a larger area.
      

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