[Digikam-devel] RAW mode decoding quality

[Gerhard Kulzer]

Hello Paco and Gilles,
I probably missed some discussion on the subject during my absence (so I'm
back): it looks to me that the quality factor selection has disappeared from
the settings menu and dcraw is now called with -q only (rawloader.cpp).

To demonstrate the bad results we get  with this simplification I've composed
an image with the same cutout from a raw file
a) decoded with the thumbnail extraction facility dcraw -e
b) with digikam
c) with dcraw -q

To me the difference is big and justifies to leave the -q 0...3 option.

Your point of view?

Gerhard

[F.J.Cruz]

El Martes, 13 de Junio de 2006 10:33, Gerhard Kulzer escribió:

> Hello Paco and Gilles,
> I probably missed some discussion on the subject during my absence (so I'm
> back): it looks to me that the quality factor selection has disappeared
> from the settings menu and dcraw is now called with -q only
> (rawloader.cpp).
>
> To demonstrate the bad results we get  with this simplification I've
> composed an image with the same cutout from a raw file
> a) decoded with the thumbnail extraction facility dcraw -e
> b) with digikam
> c) with dcraw -q
>
> To me the difference is big and justifies to leave the -q 0...3 option.
>
> Your point of view?
>
> Gerhard

I have not noticed the big differences between your pictures in my images, but
if this can be a problem for the users, well, maybe we can return to the -q
0...3 option.

In any case I've composed an image too, in similar way you have done. Please,
have a look and compare.

Paco.

Am Dienstag, 13. Juni 2006 23:26 schrieb F.J.Cruz:
Hi,
> I have not noticed the big differences between your pictures in my images,
> but if this can be a problem for the users, well, maybe we can return to
> the -q 0...3 option.

yes!!! There is a huge quality difference between these modes but every has
its own pros and cons. That why the option should be
- in
- in cleartext and not in number form and
- it would be better, if you can apply the q-value somehow in the
raw-converting process and not as a fixed default value.
 
You do not see difference when you take a thumpnail sized image, you have to
view it 1:1. Please see the details on
http://www.aim-dtp.net/aim/digicam/dcraw/vng-ahd-comparison.htm
and look at the crops.
You will see AHD (q=3) has a completely different behavior in decoding fine
structures than vng.

Bye

  Thorsten

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[Gerhard Kulzer]

On Wednesday 14 June 2006 09:09, Thorsten Schnebeck wrote:
> Am Dienstag, 13. Juni 2006 23:26 schrieb F.J.Cruz:
> Hi,
>
> > I have not noticed the big differences between your pictures in my
> > images, but if this can be a problem for the users, well, maybe we can
> > return to the -q 0...3 option.
Maybe these differences are more pronounced with certain camera models? I use
EOS350D.

> yes!!! There is a huge quality difference between these modes but every has
> its own pros and cons. That why the option should be
> - in
> - in cleartext and not in number form and
> - it would be better, if you can apply the q-value somehow in the
> raw-converting process and not as a fixed default value.

I very much subscribe to this wish. In fact I change the raw settings
constantly regarding noise filtering and quality (in the end if dcraw were
fast enough I could leave it at the best settings all the time, I change only
to gain speed when I can). It would be good to have easy access to the
settings:
a) at least group IO files and Color Management as successive, adjacent items
(now I have to scroll down)
b) provide some quick interface to raw decoding (could be popup window with
raw settings or another sidebar tab with raw settings)

Gerhard

> You do not see difference when you take a thumpnail sized image, you have
> to view it 1:1. Please see the details on
> http://www.aim-dtp.net/aim/digicam/dcraw/vng-ahd-comparison.htm
> and look at the crops.
> You will see AHD (q=3) has a completely different behavior in decoding fine
> structures than vng.
>
> Bye
>
>   Thorsten
>
> _______________________________________________
> Digikam-devel mailing list
> [hidden email]
> https://mail.kde.org/mailman/listinfo/digikam-devel

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[Gilles Caulier-2]

Le Mardi 13 Juin 2006 10:33, Gerhard Kulzer a écrit :
> Hello Paco and Gilles,
> I probably missed some discussion on the subject during my absence (so I'm
> back): it looks to me that the quality factor selection has disappeared

No, the raw quality setting is always here. It's more easy to understand an
algorithm name instead a simple number (0, 2, or 3 - 1 is not used actually
by dcraw)

> from the settings menu and dcraw is now called with -q only
> (rawloader.cpp).
>
> To demonstrate the bad results we get  with this simplification I've
> composed an image with the same cutout from a raw file
> a) decoded with the thumbnail extraction facility dcraw -e

You trying to compare an embeded JPEG image used to display picture on a TV
screen with a full quality RAW image (:=)))

> b) with digikam
> c) with dcraw -q

It's the same, but unforget the ICC workflow in digiKam !

Gilles
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Am Mittwoch 14 Juni 2006 23:15 schrieb Caulier Gilles:
> Le Mardi 13 Juin 2006 10:33, Gerhard Kulzer a écrit :
> > To demonstrate the bad results we get  with this simplification I've
> > composed an image with the same cutout from a raw file
> > a) decoded with the thumbnail extraction facility dcraw -e
>
> You trying to compare an embeded JPEG image used to display picture on a TV
> screen with a full quality RAW image (:=)))

As Gerald use an EOS 350d:
The so called thumbnail can be a full sized and developed JPEG embedded into
the CR2-RAW file. So, you can compare it, but you should compare details and
not downsized photos.  

Bye

  Thorsten

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[Gerhard Kulzer]

On Wednesday 14 June 2006 23:15, Caulier Gilles wrote:

> Le Mardi 13 Juin 2006 10:33, Gerhard Kulzer a écrit :
> > Hello Paco and Gilles,
> > I probably missed some discussion on the subject during my absence (so
> > I'm back): it looks to me that the quality factor selection has
> > disappeared
>
> No, the raw quality setting is always here. It's more easy to understand an
> algorithm name instead a simple number (0, 2, or 3 - 1 is not used actually
> by dcraw)
>
> > from the settings menu and dcraw is now called with -q only
> > (rawloader.cpp).
> >
> > To demonstrate the bad results we get  with this simplification I've
> > composed an image with the same cutout from a raw file
> > a) decoded with the thumbnail extraction facility dcraw -e
>
> You trying to compare an embeded JPEG image used to display picture on a TV
> screen with a full quality RAW image (:=)))

Yes and no. What I wanted to demonstrate is that the -q option seems to give
the same resolution as the embedded thumbnail jpg (which is really
astonishing). All the 3 examples of my attachment are crops from the 100%
zoom sizes.
>
> > b) with digikam
> > c) with dcraw -q
 actually I ment dcraw -q 3 as written on the picture.

> It's the same, but unforget the ICC workflow in digiKam !
I don't understand what you want to say here.

> Gilles
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[Gilles Caulier-2]

Le Mercredi 14 Juin 2006 22:31, Gerhard Kulzer a écrit :

> On Wednesday 14 June 2006 23:15, Caulier Gilles wrote:
> > Le Mardi 13 Juin 2006 10:33, Gerhard Kulzer a écrit :
> > > Hello Paco and Gilles,
> > > I probably missed some discussion on the subject during my absence (so
> > > I'm back): it looks to me that the quality factor selection has
> > > disappeared
> >
> > No, the raw quality setting is always here. It's more easy to understand
> > an algorithm name instead a simple number (0, 2, or 3 - 1 is not used
> > actually by dcraw)
> >
> > > from the settings menu and dcraw is now called with -q only
> > > (rawloader.cpp).
> > >
> > > To demonstrate the bad results we get  with this simplification I've
> > > composed an image with the same cutout from a raw file
> > > a) decoded with the thumbnail extraction facility dcraw -e
> >
> > You trying to compare an embeded JPEG image used to display picture on a
> > TV screen with a full quality RAW image (:=)))
>
> Yes and no. What I wanted to demonstrate is that the -q option seems to
> give the same resolution as the embedded thumbnail jpg (which is really
> astonishing). All the 3 examples of my attachment are crops from the 100%
> zoom sizes.
>
> > > b) with digikam
> > > c) with dcraw -q
>
>  actually I ment dcraw -q 3 as written on the picture.
>
> > It's the same, but unforget the ICC workflow in digiKam !
>
> I don't understand what you want to say here.

well, when you compare digiKam and dcraw, if digiKam color management is
enabled, you need to reproduce this workflow with dcraw (look icc profiles
options)

gilles
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