Bug 484872 (black, crush, gwenview) - Grayscale darks are clipped !
Summary: Grayscale darks are clipped !
Status: REPORTED
Alias: black, crush, gwenview
Product: gwenview
Classification: Applications
Component: general (show other bugs)
Version: 24.02.1
Platform: Manjaro Linux
: NOR grave
Target Milestone: ---
Assignee: Gwenview Bugs
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2024-04-01 15:00 UTC by Adolfo Rodrigues
Modified: 2025-03-19 09:33 UTC (History)
3 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
File to quickly show the issue. (12.11 KB, image/png)
2024-04-01 15:00 UTC, Adolfo Rodrigues
Details
Image comparing what gwenview shows to what it should be showing like rawtherapee (38.60 KB, image/png)
2024-04-01 15:03 UTC, Adolfo Rodrigues
Details
Info about Grayscale-Photography.png (62.56 KB, image/png)
2024-04-13 07:20 UTC, Mirco Miranda
Details
Another comparison (99.56 KB, image/png)
2024-04-13 16:50 UTC, Adolfo Rodrigues
Details
gimp vs gwenview (71.62 KB, image/png)
2024-04-13 16:55 UTC, Adolfo Rodrigues
Details
Grayscale-Photography with sRGB profile embedded (13.78 KB, image/png)
2024-04-14 06:52 UTC, Mirco Miranda
Details
attachment-3025568-0.html (2.09 KB, text/html)
2024-04-14 08:25 UTC, Adolfo Rodrigues
Details
attachment-3027739-0.html (2.73 KB, text/html)
2024-04-14 08:35 UTC, Adolfo Rodrigues
Details

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Description Adolfo Rodrigues 2024-04-01 15:00:58 UTC
Created attachment 168021 [details]
File to quickly show the issue.

STEPS TO REPRODUCE
1. Open the attached grayscale file with kolourpaint, any browser or rawtherapee

OBSERVED RESULT
gwenview has black crush

EXPECTED RESULT
Image like rawtherapee

Example screenshot:
https://ibb.co/VWsvDpF
Comment 1 Adolfo Rodrigues 2024-04-01 15:03:32 UTC
Created attachment 168022 [details]
Image comparing what gwenview shows to what it should be showing like rawtherapee
Comment 2 Mirco Miranda 2024-04-13 07:18:25 UTC
(In reply to Adolfo Rodrigues from comment #1)
> Created attachment 168022 [details]
> Image comparing what gwenview shows to what it should be showing like
> rawtherapee

I did some checks and the correct view seems to be that of GwenView:
The PNG file contains only the gAMA chunk set to 2.2. In this case, according to the specifications (https://www.w3.org/TR/2003/REC-PNG-20031110/#11gAMA), you must use sRGB primaries with a gamma curve of 2.2.
However, if you ignore curve and color management and set an sRGB color profile (if you open with GIMP it says in the title that it uses an sRGB profile for that image) or use a program that does not use color information, the displayed image will be more clear.
Comment 3 Mirco Miranda 2024-04-13 07:20:38 UTC
Created attachment 168446 [details]
Info about Grayscale-Photography.png

Inspection of sections contained within the PNG.
Comment 4 Adolfo Rodrigues 2024-04-13 16:50:06 UTC
Created attachment 168464 [details]
Another comparison
Comment 5 Adolfo Rodrigues 2024-04-13 16:51:31 UTC
Comment on attachment 168464 [details]
Another comparison

gwenview is not showing the image correctly ! It is crushing blacks and i've seen it completely blow out whites.
Comment 6 Adolfo Rodrigues 2024-04-13 16:55:47 UTC
Created attachment 168465 [details]
gimp vs gwenview

This is gimp correctly showing the image. and gwenview crushing the blacks.
Comment 7 Adolfo Rodrigues 2024-04-13 16:59:40 UTC
I have my monitor calibrated via internal lut, no ICC, qwenview is definately crushing blacks.
Comment 8 Mirco Miranda 2024-04-14 06:52:46 UTC
Created attachment 168500 [details]
Grayscale-Photography with sRGB profile embedded
Comment 9 Mirco Miranda 2024-04-14 07:35:57 UTC
(In reply to Adolfo Rodrigues from comment #7)
> I have my monitor calibrated via internal lut, no ICC, qwenview is
> definately crushing blacks.

In latest image I added an sRGB profile to your PNG. Now all software (GIMP and GwenView) shows similar blacks. I wrote similar because in gimp it is necessary to set the color profile of the monitor, the rendering intent (perceptual) and the black point compensation (off). By doing this I got 1/255 difference on some blacks compared to GwenView (which I have no idea how and if it uses the monitor's color profile).

That said, I can't tell you who is right about the accuracy of the scale: the problem seems to be in how the software treat the original PNG with the gamma info only. GIMP seems ignoring the gamma info and uses an sRGB profile.

All this to say that, with that PNG, it still doesn't seem like a GwenView problem to me.
Comment 10 Adolfo Rodrigues 2024-04-14 08:25:27 UTC
Created attachment 168501 [details]
attachment-3025568-0.html

Gwenview not showing the image correctly as one would expect could lead to
erroneous monitor corrections. Gwenview should show the image exactly like
any other image viewer , even a browser shows it correctly!! I just
reported the situation that WILL at some point cause someone issues
unnecessarily. Give a option , a disabled option, that makes Gwenview act
like the others.

A domingo, 14/04/2024, 08:35, Mirco Miranda <bugzilla_noreply@kde.org>
escreveu:

> https://bugs.kde.org/show_bug.cgi?id=484872
>
> --- Comment #9 from Mirco Miranda <mircomir@gmail.com> ---
> (In reply to Adolfo Rodrigues from comment #7)
> > I have my monitor calibrated via internal lut, no ICC, qwenview is
> > definately crushing blacks.
>
> In latest image I added an sRGB profile to your PNG. Now all software
> (GIMP and
> GwenView) shows similar blacks. I wrote similar because in gimp it is
> necessary
> to set the color profile of the monitor, the rendering intent (perceptual)
> and
> the black point compensation (off). By doing this I got 1/255 difference on
> some blacks compared to GwenView (which I have no idea how and if it uses
> the
> monitor's color profile).
>
> That said, I can't tell you who is right about the accuracy of the scale:
> the
> problem seems to be in how the software treat the original PNG with the
> gamma
> info only. GIMP seems ignoring the gamma info and uses an sRGB profile.
>
> All this to say that, with that PNG, it still doesn't seem like a GwenView
> problem to me.
>
> --
> You are receiving this mail because:
> You reported the bug.
> You are on the CC list for the bug.
Comment 11 Adolfo Rodrigues 2024-04-14 08:35:18 UTC
Created attachment 168502 [details]
attachment-3027739-0.html

Your image indeed fixed the disparity but like I said, this will lead to
issues ! My mom would have never guessed.. so I still argue gwenview should
act like the other software for sake of not having surprises. Like I said,
make it a disabled option.

On Sun, Apr 14, 2024 at 9:25 AM Adolfo Rodrigues <adolfotregosa@gmail.com>
wrote:

> Gwenview not showing the image correctly as one would expect could lead to
> erroneous monitor corrections. Gwenview should show the image exactly like
> any other image viewer , even a browser shows it correctly!! I just
> reported the situation that WILL at some point cause someone issues
> unnecessarily. Give a option , a disabled option, that makes Gwenview act
> like the others.
>
> A domingo, 14/04/2024, 08:35, Mirco Miranda <bugzilla_noreply@kde.org>
> escreveu:
>
>> https://bugs.kde.org/show_bug.cgi?id=484872
>>
>> --- Comment #9 from Mirco Miranda <mircomir@gmail.com> ---
>> (In reply to Adolfo Rodrigues from comment #7)
>> > I have my monitor calibrated via internal lut, no ICC, qwenview is
>> > definately crushing blacks.
>>
>> In latest image I added an sRGB profile to your PNG. Now all software
>> (GIMP and
>> GwenView) shows similar blacks. I wrote similar because in gimp it is
>> necessary
>> to set the color profile of the monitor, the rendering intent
>> (perceptual) and
>> the black point compensation (off). By doing this I got 1/255 difference
>> on
>> some blacks compared to GwenView (which I have no idea how and if it uses
>> the
>> monitor's color profile).
>>
>> That said, I can't tell you who is right about the accuracy of the scale:
>> the
>> problem seems to be in how the software treat the original PNG with the
>> gamma
>> info only. GIMP seems ignoring the gamma info and uses an sRGB profile.
>>
>> All this to say that, with that PNG, it still doesn't seem like a GwenView
>> problem to me.
>>
>> --
>> You are receiving this mail because:
>> You reported the bug.
>> You are on the CC list for the bug.
>
>