Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Image Processing => Topic started by: gimpaddict on December 18, 2006, 04:42:17 pm
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I figured out how to do the Tone Mapper adjustment from LightZone in Gimp/Photoshop. This tutorial is Gimp specific, but would easily translate to Photoshop (and work better with the 16-bit engine). The tone mapper decreases global contrast while increasing local contrast. Unlike the USM local contrast enhancement trick which slightly increases global contrast.
http://gimpaddict.googlepages.com/tonemapper.html (http://gimpaddict.googlepages.com/tonemapper.html)
I hope you find it useful!
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Thanks, it seems that this does a similar job to shadow / highlight in PS. It certainly lifts the shadows and does leave halo's if you are not careful.
Ian
http://www.colourperfect.co.uk (http://www.colourperfect.co.uk)
I figured out how to do the Tone Mapper adjustment from LightZone in Gimp/Photoshop. This tutorial is Gimp specific, but would easily translate to Photoshop (and work better with the 16-bit engine). The tone mapper decreases global contrast while increasing local contrast. Unlike the USM local contrast enhancement trick which slightly increases global contrast.
http://gimpaddict.googlepages.com/tonemapper.html (http://gimpaddict.googlepages.com/tonemapper.html)
I hope you find it useful!
[a href=\"index.php?act=findpost&pid=91252\"][{POST_SNAPBACK}][/a]
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Well, it's a new and more complicated way to simulate simple High Pass filtering. ;-)
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Well, it's a new and more complicated way to simulate simple High Pass filtering. ;-)
[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=91902\")
Hehe, almost everything in the gimp is more complicated unless you want to write a script .
It is very similar to a high pass filter. However, a slight variation that keeps it from desaturating the image: the guassian blurred image is desaturated and then set to a higher opacity. In a traditional high pass the guassian blurred layer is inverted (but not desaturated) and then set to 50%. If you were to just set the gaussian blurred layer to a higher opacity than 50% in a traditional high pass filter, it would tend to lower saturation. So, you could look at this as a hybrid between a contrast mask and a high pass filter.
I show a comparison of high pass, this tone mapper technique and several others here:
[a href=\"http://gimpaddict.googlepages.com/contrastcomp.html]http://gimpaddict.googlepages.com/contrastcomp.html[/url] (might be slow to load on a dialup connection).
I've been looking more carefully at the lightzone tone mapper. While this process does a decent job of emulating their results, it still is somewhat different.
Note: if you have an image that needs a really strong contrast reduction, you're better off using a full blown tone mapper algorithm like reinhard, drago, or fattal (via pfstools for instance).
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It is very similar to a high pass filter. However, a slight variation that keeps it from desaturating the image: the guassian blurred image is desaturated and then set to a higher opacity.
[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=92344\")
Obviously, I noticed some difference between plain highpass and this variation. Well, I'd prefer different merge mode to prevent the desaturation but frankly, for quite some time now I prefer different way of manipulating local contrast, different from highpass:
[a href=\"http://photoshop.msk.ru/aspd/]http://photoshop.msk.ru/aspd/[/url]
but you are supposed to be having problems emulating it with GIMP :-)