Cameras are much more likely to generate a soft focus under low light. The Smart Sharpen filter has the most options of any sharpening filter built into Photoshop. It allows you to choose the sharpening algorithm as well as control the amount of sharpening in shadow and highlight areas. This filter can produce dramatically better quality, but do not expect results like you see in a TV police drama.

Using Smart Sharpen

To get started, open the file in question and go to Filter > Sharpen > Smart Sharpen. Then position the image in the preview window so you can better see the area in question. From there, you can adjust the controls in the Sharpen section:

  • Amount: Sets the amount of sharpening. A higher value increases contrast between edge pixels, which gives the appearance of more sharpness.
  • Radius: Determines the number of pixels surrounding the edge pixels that will be affected by the sharpening. A greater radius value means that edge effects will be more obvious, as will the sharpening.
  • Reduce Noise: Helps to eliminate noise in the sharpened areas.

You can also use the Remove drop-down for further control:

  • Gaussian Blur: Is used by the Unsharp Mask filter. It works well on images that appear slightly out of focus.
  • Lens Blur: Detects edges and detail in an image. It provides finer sharpening of detail and can reduce halos caused by sharpening.
  • Motion Blur: Attempts to reduce the effects of blur caused by camera or subject movement. You will need to set the Angle control if you choose Motion Blur.

Refining the sharpening of dark and light areas

You can refine the sharpening of dark and light areas — try expanding the Shadows / Highlights section. These controls should be used if you start to see halos in light or dark areas:

  • Fade Amount: Adjusts the amount of sharpening in the highlights or shadows regions.
  • Tonal Width: Controls the range of tones in the shadows or highlights that are modified. Smaller values restrict the adjustments to smaller regions.
  • Radius: Controls the size of the area around each pixel that determines if a pixel is considered a shadow or a high-light. Moving the slider to the left specifies a smaller region; moving the slider to the right defines a larger region.

When you’re done, click OK to apply the filter. Check out the before and after below: