On 2012-12-30 22:46, Matt Feifarek wrote:
It is a simple gamma curve; that's what "base curve" is. But it seems
that it's different according to sensor, to firmware, etc.
Well, I would allow for slight differences, but the differences do
appear to be rather heavy.
Two cameras from two vendors that have the same sensor will produce
different looking jpeg images; it would of course be up to you which
is more "natural" looking. But with RAW files, I think the data
exported is the same from the sensor (though the files themselves are
different, according to manufacturers). I think the Dt authors have
attempted to duplicate these stock curves through estimation.
I suppose you are correct.
If you don't find these presets to be natural, you can always make
your own preset.
This is exactly my problem. I wanted something "authorative". It seems
this does not exist.
Thank you very much for your help!
Regards,
Eckhart Pedersen
On Sun, Dec 30, 2012 at 4:43 PM, Eckhart Pedersen
<[email protected] <mailto:[email protected]>>
wrote:
On 2012-12-30 22:37, Markus Jung wrote:
> You assume the RAW image is neutral. This assumption is wrong.
But isn't the entire point of an input profile to fix this?
> Camera sensors are far away from being linear, especially at the
very
> bright tones. The base curve corrects this distorted response
curve and
> makes the images look similar to the OOC JPEG results.
Shouldn't this be a simple gamma curve? No fancy camera specific
handling?
> If you do not
> like the style of your camera vendor you can modify the base
curve to
> fit your own needs. I expect a more neutral (less contrasty)
base curve
> to look similar like the original one.
>
> The new alternate base curves provided by Pascal (many thanks!) have
> shown in an impressive way how important a good base curve is. I
> reworked a lot of images and the new base curve improved most of
them by
> a large amount. The color rendering (especially for skin tones)
improved
> a lot, too.
>
> And another observation: Base curve and tone curve behave
different. I
> tried some adjustments with tone curve and failed, the same tweaks
> worked well with base curve.
>
> Regards,
> Markus
>
> Am 30.12.2012 22 <tel:30.12.2012%2022>:11, schrieb Marie-Noëlle
Augendre:
>> First thing I do when I begin to work on a picture is
deactivate the base
>> curve. I'd rather start from something as neutral as possible,
than to make
>> modifications/corrections over something that is made
automatically and
>> whose effect I don't like.
>> Then I use the tone curve to make the modifications I want, and
that are
>> different for each picture.
>>
>> Marie-Noëlle
>>
>> 2012/12/30 Markus Jung <[email protected] <mailto:[email protected]>>
>>
>>> You must not disable basecurve, the images looks like if you
did this.
>>>
>>> Sensors differ in the way how they respond to brightness, the
basecurve
>>> expresses how the sensor values have to be interpreted.
>>>
>>> Regards,
>>> Markus
>>>
>>> Am 30.12.2012 22 <tel:30.12.2012%2022>:08, schrieb Eckhart
Pedersen:
>>>> Hi all,
>>>>
>>>> I have tried very hard to understand color management for
years, and I
>>>> think I have finally understood the basics. I have now
calibrated my
>>>> Dell U2410 with an i1 display pro colorimeter + DispcalGUI,
installied
>>>> the profile system wide, and am now using this profile in
darktable. I
>>>> have even verified the calibration and profile using the
colorimeter and
>>>> everything seems to be ok.
>>>>
>>>> Calibration was done in standard mode of the display, 30
Brightness, 50
>>>> contrast, and 6500K black body as whitepoint target.
>>>>
>>>> If I now load a raw image from my Canon EOS 5D II in
darktable and
>>>> disable all processing (except sharpening), I would expect to
get a
>>>> usable/neutral rendition of the photo on my display. However,
the photos
>>>> look very dull/muted. Since darktable comes with an existing
input
>>>> profile for the 5D II (it does, doesn't it?) I would expect
the default
>>>> look to look more or less natural, without having to fiddle
with curves,
>>>> saturation, or contrast in any way. But this does not seem to
be true.
>>>> It looks completely wrong.
>>>>
>>>> You can find an example image here.
>>>>
>>>> *raw* *CR2*: http://cornergraf.net/darktable.org/raw.CR2
>>>> *exported JPG* with everything off, except sharpening:
>>>> http://cornergraf.net/darktable.org/muted2.jpg
>>>> *exported JPG* with black level +0.10, and exposure +1.3:
>>>> http://cornergraf.net/darktable.org/proper2.jpg
>>>>
>>>> Please help me understand what is going on here. Is this the
way the
>>>> files should look like straight out of the camera and with no
>>>> processing? Is my display calibrated or profiled incorrectly?
What do
>>>> you get when you look at the exported JPG files, which one
looks more
>>>> natural?
>>>>
>>>> I would greatly appreciate any help you can give me.
>>>>
>>>> Regards,
>>>> Eckhart
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
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>>
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