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LAB Sharpen

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AK-LABSharpen.scm2.36 KB

This script does LAB sharpening using the unsharp mask in the luminance (L) layer. It decomposes the image into LAB layers, sharpens the luminance layer (using the supplied settings), and then recomposes the image. The interface is the same as the unsharp mask (radius, amount, threshold), but the filter is only applied to the luminance layer.

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This is indeed a great tool as it saves a lot of manual work. Here is an idea to further improvement. It is based on Dan Margulis' observation that when sharpening with an unsharp mask you often want to separate the lightening and darkening effect in two separate layers and then apply about half as much lightening as darkening. This makes the pictures look more natural.

So what I do with your script is: Make two duplicates of the original picture so you keep the original picture unchanged, apply AK-LABSharpen to the top duplicate layer and then make an extra copy of this sharpened layer. The mode of the two sharpened layers is then set to Lighten only (top layer) and Darken only (below top layer) and the opacity of the upper layer is set to 50 %. Now merge down the Darken only layer and next the Lighten only layer. Now you have a sharpened layer on top of your original picture and you can then adjust the sharpening effect by setting the opacity of the sharpened layer. Voila!

If this process could be automated too it would improve this great tool further :-)

One of the best sharpening plugins around!

Looks good to me. Installed without a problem and works well. Certainly takes the hard work out of sharpening just the image luminance. Thanks for a very neat script.

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