[Digikam-devel] [Bug 204466] New: local contrast plugin issues

[Mikolaj Machowski]

https://bugs.kde.org/show_bug.cgi?id=204466

           Summary: local contrast plugin issues
           Product: digikam
           Version: unspecified
          Platform: Compiled Sources
        OS/Version: Linux
            Status: NEW
          Severity: wishlist
          Priority: NOR
         Component: Image Editor
        AssignedTo: digikam-devel at kde.org
        ReportedBy: mikmach at wp.pl


Version:            (using Devel)
Compiler:          gcc4.3.2 
OS:                Linux
Installed from:    Compiled sources

Sorry for delay but better late then never. Also I knew about answers for my
post on mail on list only through Gilles post. Below is fragment of discussion
from list with my additional comments.

---------------------------------------
>> MM
> Julien Narboux
 Julien Pontabry

> > 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
---------------------------------

Ad. 1: "Local Tone Mapping" is the best. Why not even shorter - "Tone Mapping"?

Ad. 2: About GUI - I wonder if it would be technically possible to split
functionality in profiles: Highlights/Shadows - with resctricting (or
translating somehow) sliders to effects giving "recovering" effects
Pseudo HDR - for well liked and unrealistic HDR look.

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