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Unsharp mask

I neither the patience nor the "creative graphical sense" to touch up the photos I take to look good on the web. Scanning these in is major nuisance. Dawn has put up a table of Unsharp Mask settings she use to make her great photos look sharp. I don’t know why it is named “Unsharp Mask”, when the effect is to make it sharper!

For folks like me who can’t shell out $700 for Photoshop, Gimp or Imagemagick would do just as well. Let us see what we can do with this image - it is a traditional lamp from Kerala.

In Gimp, it is easy. Open the image, right click on the image, choose Filters -> Enhance -> Unsharp Mask.

For scripting this, ImageMagick might be better. Shown below are the results and commands used on the original image. In -unsharp takes an argument of the form RADIUSxSIGMA. SIGMA is the standard deviation. You might want to check out all the options available for ImageMagick.

convert -antialias -unsharp 3x3 original.jpg newimage.jpg

convert -antialias -unsharp 3x5 original.jpg newimage.jpg

convert -antialias -unsharp 5x5 original.jpg newimage.jpg

• Unsharp Mask quick tips.
• Unsharp Mask in Paint Shop Pro.
• Another PhotoShop tip.
• PhotoShop study guide.

1. "The Camera is a Tool, But The Photographer Doesn't Have to Be" at http://www.evolt.org/article/The_Digital_Darkroom/22/39773/index.html is pretty good.

   Posted by: Babu on September 26, 2002 07:18 AM