[Digikam-devel] local contrast plugin

[Gilles Caulier]

Mik, i recommend you to post question to this B.K.O entry, which is
fully relevant (to have a preserved story in bugzilla, instead mailing
list)

https://bugs.kde.org/show_bug.cgi?id=145442

Gilles

2009/8/10 Julien Pontabry <julien.pontabry at ulp.u-strasbg.fr>:
> Julien Narboux a écrit :
>> Mikolaj Machowski a écrit :
>> > Hello,
>> >
>> > Looks like I've made injustice to new local contrast plugin in last DD.
>> > Only later I noticed Gilles' screenshot
>> >
>> > http://www.flickr.com/photos/digikam/3771531595/in/pool-digikam-labs
>> >
>> > Knowing what it is about I was able to play with it a bit to some success
>> > and it is great tool.
>> >
>> > But I have two problems with it:
>> >
>> > 1. Name: when you google for "local contrast" you will come with *many*
>> > sites describing one of unsharp mask techniques while this tool is much
>> > more similar in spirit to Highlighs/Shadows tools from other programs.
>> > Even "Pseudo HDR" nick would be better description. From WhatsThis I
>> > understand is sophisticated implementation of Contrast Mask technique
>> > (BTW - I wonder if it would be possible to build smart sharpening based
>> > on this plugin)
>>
>> It seems to me that this plugin does Highlights/Shadows recovery but
>> taking into account the whole picture to preserve contrast.
>> Maybe it could be called :
>> "Local Highlights/Shadow recovery"
>> "Local Tone Mapping"
>> "Spatially Varying Tone Mapping"
>>
>> Look wikipedia for the definition of tone mapping :
>>  http://en.wikipedia.org/wiki/Tone_mapping
>>
>> > 2. It is really hard to use. Only after I discovered connection with
>> > Contrast Mask I was able to grok something but still struggle with
>> > understanding what is what (eg. Stages?). Please, user documentation :)
>>
>> I guess stages are just several applications of the filter.
>> You can find documentation on the web page of Nasca Octavian PAUL
>> (http://zynaddsubfx.sourceforge.net/other/tonemapping/) upon which this
>> plugin is based.
>>
>> I think before writing proper documentation, it would be nice to wonder
>> if there is no better gui one can think of.
>> I tested using only one stage and it was fine. Does anyone has examples
>> which needs several "stages" to get a good result ?
>>
>> Julien Narboux
>>
>> ps: The plugin has still to be polished because 16bits and the progress
>> bar do not work.
>> Maybe preview could be faster using a downscaled image ? Julien, what do
>> you think about that ?
>
> I think we should first improve the plugin code to get it faster. I'm not sure
> using downscale is a good idea. See the real effect on a little part of the
> original image may be better, isn't it ?
>
> Julien
>
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