RAW Brightness vs Curves

[Leonardo Giordani]

Hi all,

I would like to ask you about a strange effect that happens when converting
RAW data; to help me explaining the situation I posted some images on

http://picasaweb.google.it/giordani.leonardo/DigiKam093#

Sorry but I'm using 0.9.3 since Ubuntu Hardy has not yet 0.9.5.

This is the problem:

I'm going to process a RAW image, you can see it in figure 01.

When I load it in RAW Image Converter it appears as in figure 02, WB is
correct but brightness is a bit low.

If I raise brightness from 3.00 to 5.00 in RAW Image Converter I experience
some quality issues: look at what happens in figure 03 to the background
flowers (the yellow ones on the right): they seems to "spread".

If I convert the RAW image with brightness 3.00 (to 16 bit TIFF) and process
it with Color->Curves..., just shifting up the middle point of the curve, I
obtain what you can see in figure 04: foreground brightness is the same as
before, but background quality is preserved.

Why does this happen? Is this an error of mine?

What about batch apply of Edit tools (like Curves) in 0.10.x or subsequent
releases?

Thank you very much

Leonardo


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On Friday 08 May 2009 16:49:45 Leonardo Giordani wrote:

>
> Why does this happen? Is this an error of mine?

No. Difference between digiKam and other RAW applications as far as I
understand (and was able to observe while working) is that digiKam process
with minimum changes from itself. Other programs usually apply some default
curves, sharpening, etc. depending on: common sense, smart algorithms trying
to "understand" image, maintaining extensive databases on what should be done
to photo depending on camera model, firmware, lens.

Frugal handling of RAW data by digiKam can be seen as bug or feature depending
on your attitude.

Myself I think this is good - less magic wand is better. BUT: because it means
more work for photographer digiKam should provide tools to speed up workflow
later when making those corrections by hand. And this element is in
development.

> What about batch apply of Edit tools (like Curves) in 0.10.x or subsequent
> releases?

I hope this will be possible with Batch Queue Manager.

m.
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