Legacy ImageMagick Discussions Archive

Hi all,

Just started using this Lightroom plugin module and wondered if someone could explain how the sharpening works? Or, if there's some pages that can be read on the net a lnk would be great.

Thanks

There are two major ways of doign sharpening in Image processing, as well as a whoe swag of intermediate and composition methods basied on these combined with other operations.

The first is kernal convolution shapening, which tryes to enhance color changes in images. this is in IM as the -sharpen operator.

The other method is to make a copy of the image and blur it. This blured image is then blended with the original image to reverse the process and sharpen the result. This is known in IM as -unsharp operation. A explaination is availabel in IM examples in Extrapolated blends
http://imagemagick.org/Usage/compose/#blend_use

A mixed method using unsharp with edge detection is explored in
http://www.gimpguru.org/Tutorials/ReducingCCDNoise/
Though this can be done in IM, knowone has published the equivalent in terms of specific IM operations.

Hi Anthony,

Thank you for a reply.

I understand the idea of Unsharp Mask, what I am trying to understand is how I can see the affect of the Mogrify sharpening before I export. Without a preview facility I could either not apply enough sharpening or over sharpen an image.

That is not something I can directly help you with. Sorry.
You will have to do some experimentation and trial and error.