Raw converter: no exif, only 8bit

Hi,

after I got the svn version running, I tried the raw converter and
experienced two problems:
1) Although in settings the output format is set to tiff 16bit I can
just get 8bit. This can't even be set in the Raw Image Converter Dialog.
2) none of the metadata of the raw image (NEF) is exported to tiff.

When I open the nef directly in the Editor and save it to tiff, this
yields 16bit. However, the image appears much to dark in the editor.
Raising the Gamma to 2 yields nearly the same impression than in the
preview. Wouldn't that be better a default. Or is there some reason not
to adjust anything, when a raw is opened directly?

CU Martin.

Btw.: Is this mailing list the right place to report these kinds of
problems?


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Le Sat, 19 May 2007 12:42:44 +0200, Martin Schmettow a écrit:

> Hi,

Hi,


> after I got the svn version running, I tried the raw converter and
> experienced two problems:
> 1) Although in settings the output format is set to tiff 16bit I can
> just get 8bit. This can't even be set in the Raw Image Converter Dialog.
> 2) none of the metadata of the raw image (NEF) is exported to tiff.

the raw converter is a kipi-plugin, not the digikam raw part. And yes,
this kipi-plugin is only 8bit at the moment.
To use the digikam raw feature, you simply have to "edit" (F4 by default)
your picture. This way of handling your raw file will honor the settings
of raw decoding you entered in digikam setup. The kipi-plugin way will
not, since it will use it's own configuration.


> When I open the nef directly in the Editor and save it to tiff, this
> yields 16bit. However, the image appears much to dark in the editor.
> Raising the Gamma to 2 yields nearly the same impression than in the
> preview. Wouldn't that be better a default. Or is there some reason not
> to adjust anything, when a raw is opened directly?

Having your RAW dark is a normal thing in 16bit mode. RAW are basically
decoded as linear. But to get something like your jpg preview, you need
to apply a non-linear transformation : you need to apply a color profile.
For example, a quite standard working profile is sRGB. sRGB is a gamma
2.2 space (near the gamma of the eyes).
But gamma 2.2 should NEVER been applied by default, since it depends on
the working profile you want to work in.

If you want to have directly a good-looking picture, use 8bit mode ;)

You can find some informations of such color-profile and gamma management
all around the web. For example : http://www.aim-dtp.net/aim/calibration/
srgb/g_spaces_srgb.htm
You will find many others in google ;)


Regards,
Guillaume



--
cdlt,
Guillaume Castagnino

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[Gilles Caulier-4]

> 2) none of the metadata of the raw image (NEF) is exported to tiff.

Duing a libtiff limitation to support Exif informations, we cannot store at this moment all Exif informations (Makernote meatadata included). Ther eis no issue with libtiff about this problem...

In the near future, next Exiv2 library will support Tiff file in writting mode. All will be solved by this way...

This is why i don't use tiff file format to convert RAW file without lost metadata. I use everytime PNG witch support loss les compression like tiff.

The PNG support in digiKam is the best actually. Try it. All metadata are save in PNG using the same way than ImageMagick do. Like this, if you post-process this file using ImageMagick (to convert for example), nothing will be lost (about metadata)

Gilles

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