[darktable-user] Lua changes for darktable 3.6

[William Ferguson]

A post detailing the lua changes for darktable 3.6 is at
https://discuss.pixls.us/t/lua-updates-for-darktable-3-6/25686


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Re: [darktable-user] exporting to Tiff

[GianLuca Sarto]

Thanks Kovcs, I will

On 01/07/21 11:35, KOVÁCS István wrote:

Hello,

You may want to try signing up on discuss.pixls.us, which is now the
recommended way to interact with the community, including the
developers. https://www.darktable.org/contact/ mentions the mailing
lists as 'last resort'.

Make sure all your applications are properly colour managed. darktable
has a utility, darktable-cmstest, that can check your display profile.
There are quite a few ways this can go wrong.
You should set a display profile in your desktop environment, open a
new command shell, and run darktable-cmstest.
Then also check the Gimp. In Edit -> Preferences -> Color management,
set 'Image display mode' to 'Color-managed display', and, just to be
certain, you may want to set the 'Monitor profile' to a specific file.
If everything is fine (as reported by darktable-cmstest), you
shouldn't need that (note that the specified profile is only used if
'Try to use the system monitor profile' is unchecked, or if it fails
to read the profile from system settings. (It might be a good idea to
back up your ~/.gimp-2.8 (or whatever version you use) directory, and
then reset Edit -> Preferences -> Color management settings before you
try setting a new profile.

There are two ways to determine the display profile; the 'X atom' and
'colord'; darktable-cmstest will check that they are set to the same
value -- and that's the one Gimp should also use.

Then check what profile you use for darktable export, and using which
profile Gimp interprets the exported file.

It's easy to sign up for discuss.pixls.us, and there you are allowed
to share images (e.g. screenshots), which could make this
investigation easier.

Kofa

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Re: [darktable-user] exporting to Tiff

[KOVÁCS István]

Hello,

You may want to try signing up on discuss.pixls.us, which is now the
recommended way to interact with the community, including the
developers. https://www.darktable.org/contact/ mentions the mailing
lists as 'last resort'.

Make sure all your applications are properly colour managed. darktable
has a utility, darktable-cmstest, that can check your display profile.
There are quite a few ways this can go wrong.
You should set a display profile in your desktop environment, open a
new command shell, and run darktable-cmstest.
Then also check the Gimp. In Edit -> Preferences -> Color management,
set 'Image display mode' to 'Color-managed display', and, just to be
certain, you may want to set the 'Monitor profile' to a specific file.
If everything is fine (as reported by darktable-cmstest), you
shouldn't need that (note that the specified profile is only used if
'Try to use the system monitor profile' is unchecked, or if it fails
to read the profile from system settings. (It might be a good idea to
back up your ~/.gimp-2.8 (or whatever version you use) directory, and
then reset Edit -> Preferences -> Color management settings before you
try setting a new profile.

There are two ways to determine the display profile; the 'X atom' and
'colord'; darktable-cmstest will check that they are set to the same
value -- and that's the one Gimp should also use.

Then check what profile you use for darktable export, and using which
profile Gimp interprets the exported file.

It's easy to sign up for discuss.pixls.us, and there you are allowed
to share images (e.g. screenshots), which could make this
investigation easier.

Kofa

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Re: [darktable-user] exporting to Tiff

[Emanuele Olivetti]

On Thu, Jul 1, 2021 at 10:52 AM GianLuca Sarto  wrote:

> Not sure if it is a color profile problem, given the monochromatic image.
>

The speed of transition from dark tones to light tones is part of the
profile, so it affects BW images as well, to my knowledge.


> The comparison is made on screen, between Darktable and Gimp.
>
> In Gimp, the image is a little darker, so shadows' detail is partially
> lost.
>
> I would have expected that the tiff in Gimp was an exact copy of DT.
>

If the comparison is on screen - and the same screen with the same
operating system - then color management "should" not differ and you are
right to expect the exact same appearance. If that is not the case, then I
tend to think that GIMP is doing something with the profile. If you were
requested to keep the original profile or convert to another one and kept
the original one... then I don't know :)
In GIMP, consider investigating Image -> Color Management -> Assign Color
Profile (or Image Properties) and see what profile is associated with that
picture and if differs from the profile you choose when exporting from DT.

Other than issues with color management I don't have any plausible
explanation for what you are experiencing.

Best,

Emanuele


> On 01/07/21 10:20, Emanuele Olivetti wrote:
>
> Howdy,
>
> What about the color profile associated with the TIFF and how was it
> managed by GIMP and by your printer?
> When you say that you "compared the Tiff with the image on DT", how did
> you do exactly?
>
> At first sight, I would say that you experienced a problem in color
> management. But correct me if I'm wrong.
>
> Best,
>
> Emanuele
>
>
> On Thu, Jul 1, 2021 at 9:23 AM GianLuca Sarto  wrote:
>
>> Hello All,
>>
>> I was working [DT v3.4.1, Linux] on a BW image, when finished, I
>> exported to Tiff, leaving Profile/Intent as Image Settings.
>>
>> Later, when I printed the image with Gimp, I noticed that the image on
>> paper was darker and some detail in the shadows was lost.
>>
>> I thought it was a limitation of the printer, but then I compared the
>> Tiff with the image on DT, it was the Tiff that had lost detail in the
>> shadows.
>>
>> Is this something to be expected when exporting? or am I missing
>> something?
>>
>> Thanks for your comments,
>>
>> -Gian
>>
>>
>>
>> 
>> darktable user mailing list
>> to unsubscribe send a mail to
>> darktable-user+unsubscr...@lists.darktable.org
>>
>>


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Re: [darktable-user] exporting to Tiff

[GianLuca Sarto]

Not sure if it is a color profile problem, given the monochromatic image.

The comparison is made on screen, between Darktable and Gimp.

In Gimp, the image is a little darker, so shadows' detail is partially lost.

I would have expected that the tiff in Gimp was an exact copy of DT.


On 01/07/21 10:20, Emanuele Olivetti wrote:

Howdy,

What about the color profile associated with the TIFF and how was it 
managed by GIMP and by your printer?
When you say that you "compared the Tiff with the image on DT", how 
did you do exactly?


At first sight, I would say that you experienced a problem in color 
management. But correct me if I'm wrong.


Best,

Emanuele


On Thu, Jul 1, 2021 at 9:23 AM GianLuca Sarto > wrote:


Hello All,

I was working [DT v3.4.1, Linux] on a BW image, when finished, I
exported to Tiff, leaving Profile/Intent as Image Settings.

Later, when I printed the image with Gimp, I noticed that the
image on
paper was darker and some detail in the shadows was lost.

I thought it was a limitation of the printer, but then I compared the
Tiff with the image on DT, it was the Tiff that had lost detail in
the
shadows.

Is this something to be expected when exporting? or am I missing
something?

Thanks for your comments,

-Gian



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Re: [darktable-user] exporting to Tiff

[Emanuele Olivetti]

Howdy,

What about the color profile associated with the TIFF and how was it
managed by GIMP and by your printer?
When you say that you "compared the Tiff with the image on DT", how did you
do exactly?

At first sight, I would say that you experienced a problem in color
management. But correct me if I'm wrong.

Best,

Emanuele


On Thu, Jul 1, 2021 at 9:23 AM GianLuca Sarto  wrote:

> Hello All,
>
> I was working [DT v3.4.1, Linux] on a BW image, when finished, I
> exported to Tiff, leaving Profile/Intent as Image Settings.
>
> Later, when I printed the image with Gimp, I noticed that the image on
> paper was darker and some detail in the shadows was lost.
>
> I thought it was a limitation of the printer, but then I compared the
> Tiff with the image on DT, it was the Tiff that had lost detail in the
> shadows.
>
> Is this something to be expected when exporting? or am I missing something?
>
> Thanks for your comments,
>
> -Gian
>
>
>
> 
> darktable user mailing list
> to unsubscribe send a mail to
> darktable-user+unsubscr...@lists.darktable.org
>
>


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[darktable-user] exporting to Tiff

[GianLuca Sarto]

Hello All,

I was working [DT v3.4.1, Linux] on a BW image, when finished, I 
exported to Tiff, leaving Profile/Intent as Image Settings.


Later, when I printed the image with Gimp, I noticed that the image on 
paper was darker and some detail in the shadows was lost.


I thought it was a limitation of the printer, but then I compared the 
Tiff with the image on DT, it was the Tiff that had lost detail in the 
shadows.


Is this something to be expected when exporting? or am I missing something?

Thanks for your comments,

-Gian



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