[Gimp-docs] [Gimp-developer] Retinex doc

[ben]

It is too much work :)

So, here we go. I'll rewrite the whole section starting from "These 
options ...".

from http://docs.gimp.org/en/plug-in-retinex.html

If anyone wants to refine what I wrote over the old article, or feels I 
made a mistake, please don't hesitate to reply.

===
These options call for notions that only mathematicians and imagery 
engineers can understand. In actual practice, the user has to grope 
about for the best setting. However, the following explanations should 
help out the experimented Gimp user.

Level
Here is what the plug-in author writes on his site 
(www-prima.inrialpes.fr/pelisson/MSRCR.php): “To characterize color 
variations and the lightor, we make a difference between (gaussian) 
filters responses at different scales. These parameters allow to specify 
how to allocate scale values between min scale (sigma 2.0) and max 
(sigma equal to the image size)”...

Uniform: Uniform tends to treat both low and high intensity areas fairly.

Low: As a rule of thumb, low does "flare up" the lower intensity areas 
on the image.

High: high tends to "bury" the lower intensity areas in favor of a 
better rendering of the clearer areas of the image.


Scale
Determines the depth of the Retinex scale. Minimum value is 16, a value 
providing gross, unrefined filtering. Maximum value is 250. Optimal and 
default value is 240.


Scale division
Determines the number of iterations in the multiscale Retinex filter. 
The minimum required, and the recommended value is three. Only one or 
two scale divisions removes the multiscale aspect and falls back to a 
single scale Retinex filtering. A value that is too high tends to 
introduce noise in the picture.


Dynamic
As the MSR algorithm tends to make the image lighter, this slider allows 
you to adjust color saturation contamination around the new average 
color. A higher value means less color saturation. This is definitely 
the parameter you want to tweak for optimal results, because its effect 
is extremely image-dependent.
===



Axel Wernicke wrote:
> Hi Ben,
> 
> you could write the documentation in docbook xml and send a patch to the 
> docs list. If this is to technical or to much work, you could also write 
> the documentation and sent it as plain text or odf to me (axel.wernicke 
> [at] gmail dot com).
> 
> 
> Greetings,
> 
> lexA
> 
> 
> Am 07.10.2007 um 17:43 schrieb ben:
> 
>> Hi everyone,
>>
>> I wanna complete the documentation of the Retinex page:
>>
>> http://docs.gimp.org/en/plug-in-retinex.html
>>
>> How can I do it, just submit a text in an email to the list?
>>
>> Cheerz
>>
>> Ben