[Digikam-users] Improving photos

[Gilles Caulier]

>
>
> In 99,99999% of all cases I use 8bit (publishers anyway scale down 16bit
> images to 8 before printing, so what should I grapple with much larger
> files :-)  I use 16bit only, if there are difficult parts in the shadows
> or
> lights, so I can get out more of it.


I would just to give my viewpoint about shadows/highlight with 16 bits color
depth.

16 bits color depth want mean than each pixels have a bigger color
resolution than 8 bits. But this is not want mean than you will enlarge the
CCD dynamic range ! It still the same especially with highlight.

Of course the 16 bits color depth is better to process color adjustments for
the light properlly exposed.

The CCD are different than Human eyes and do not restitute the highlight
properlly. This is why if you want to render an image in the same way than
human eyes, you need to do High Range picture, using bracketing with camera.
Typically like this :

- One picture under exposed to get HighLight
- One picture properlly exposed to get MidLight
- One picture over exposed to get ShadowLight

... and afer, you merge all in the same picture, using a specific format
like OpenEXR  for ex.

This is explained certainly better than mine in wikipedia :

http://en.wikipedia.org/wiki/High_dynamic_range_imaging

And the imagering technic is called Tone Mapping. look here :

http://en.wikipedia.org/wiki/Tone_mapping

Like you can see, the HDR pictures are really  really nice, but of course
this technic can be only used with static subjects. Generally, we using a
tripod during camera shots.

In the future, i would to have a plugin to process HDR image in digiKam
using a serie of bracketed shots. It's not very complicated to do.

Note than SuperCCD from Fuji is the only solution to improve the dynamic
range of digital camera :

http://en.wikipedia.org/wiki/Super_CCD

... and you can find some explainations of Dynamic Range here :

http://www.dpreview.com/learn/?/Glossary/Digital_Imaging/dynamic_range_01.htm

.. and the relation with famous histogram...


Gilles
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.kde.org/pipermail/digikam-users/attachments/20070418/a104771a/attachment.html>