[Digikam-devel] local contrast plugin

[Julien Narboux]

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 ?