Steve's Template

1
Steve Cannistra, Dark Halo Removal
Dark halos around stars can result from overly
aggressive use of deconvolution or unsharp
masking.
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Steve Cannistra, Dark Halo Removal
Setting up the technique in Photoshop
1. Duplicate the layer (Layer, Duplicate
Layer).

• Smooth the top layer (Filter, Noise, Median). A
  radius of 5
• is a good starting point.

3. Assign the top layer to lighten mode.
4. Create a top layer mask (Layer, Add Layer
Mask, Hide All).
5. The layer should now look like this (next
slide)
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Steve Cannistra, Dark Halo Removal
Lighten mode
Original layer
Mask
Median smoothed layer
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Steve Cannistra, Dark Halo Removal
Removing the halos is accomplished by painting
the mask white in the areas of affected stars
1. Select the paint brush tool. Make certain
color is set to white.

• Adjust the paint brush diameter so that it is
  approximately
• the same size as the stars.

3. Click on the black mask area to make it
active.

• Paint over the affected stars to reveal the
  overlying
• lighter regions of the smoothed top layer. The
  dark halos
• around the stars should nicely fill in.

5. The layer should now look like this (next
slide)
5
Steve Cannistra, Dark Halo Removal
Final image with halos removed
Mask with white areas representing locations
of affected stars