Colours, digikam and firefox

[Alastair Burt]

When I have a photo fresh from my camera in JPEG format, the photo looks
the same in digikam and firefox. When I open the photo in digikam's
editor, showfoto, carry out *no edting*, and ask the editor to "save as"
another JPEG file, the situation is quite different. Digikam, gwenview
and image magick's display all show me something that looks just like
the original version. But firefox and gimp -- both GTK-based programs, I
note-- show me a photo with a heavy blue tinge. This is also true if I
save the original file in PNG format.

I am perplexed as to why photos have different colours in digikam and
firefox. Currently, my suspicion lies with the handling of colour
management. Getting the image magick display program to output info on
the files, I see one difference between the original and the "saved as"
JPEG version is that the saved version has "Profile-icc sRGB". Is this
being handled differently in GTK-based programs? And is there a way for
me to be more sure that what I see in digikam bears some resemblance to
what it will look like in people's browsers?

I have just experienced this phenomenon with the following two JPEG
files on kubuntu jaunty with digikam 0.10.0 and firefox 3.5.5, but I
have seen the same with other photos and other versions of kubuntu,
digikam and firefox.

  original:
http://farm3.static.flickr.com/2746/4127187151_b5e291f2b8_o_d.jpg
<http://farm3.static.flickr.com/2746/4127187151_b5e291f2b8_o_d.jpg>
  saved as version:
http://farm3.static.flickr.com/2654/4127958878_dccbeb8db7_o_d.jpg
<http://farm3.static.flickr.com/2654/4127958878_dccbeb8db7_o_d.jpg>

-- Alastair
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[Micha? Smoczyk]

Alastair Burt pisze:

> I am perplexed as to why photos have different colours in digikam and
> firefox. Currently, my suspicion lies with the handling of colour
> management. Getting the image magick display program to output info on
> the files, I see one difference between the original and the "saved as"
> JPEG version is that the saved version has "Profile-icc sRGB". Is this
> being handled differently in GTK-based programs? And is there a way for
> me to be more sure that what I see in digikam bears some resemblance to
> what it will look like in people's browsers?

Hmm, since 3.5 version (if I am right) Firefox browser carry about
color profiles. See for example:
http://hacks.mozilla.org/2009/06/color-correction/

I think it may be caused by this feature. Try to change firefox
settings connected with icc (about:config).

> I have just experienced this phenomenon with the following two JPEG
> files on kubuntu jaunty with digikam 0.10.0 and firefox 3.5.5, but I
> have seen the same with other photos and other versions of kubuntu,
> digikam and firefox.

For me the same: in firefox 3.5.5 your images look different.

--
/\/\ichau, admin [malpka] nocnyrzepin [kropa] net
http://www.nocnyrzepin.net


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[Alastair Burt]

Micha? Smoczyk wrote:

> Alastair Burt pisze:
>
>> I am perplexed as to why photos have different colours in digikam and
>> firefox. Currently, my suspicion lies with the handling of colour
>> management. Getting the image magick display program to output info on
>> the files, I see one difference between the original and the "saved as"
>> JPEG version is that the saved version has "Profile-icc sRGB". Is this
>> being handled differently in GTK-based programs? And is there a way for
>> me to be more sure that what I see in digikam bears some resemblance to
>> what it will look like in people's browsers?
>
> Hmm, since 3.5 version (if I am right) Firefox browser carry about
> color profiles. See for example:
> http://hacks.mozilla.org/2009/06/color-correction/
>
> I think it may be caused by this feature. Try to change firefox
> settings connected with icc (about:config).

Indeed, setting gfx.color_management.mode to 0 and restarting firefox
removed the blue tinge. I wonder what is happening here. And there are
still the gimp peculiarities. It would seem from the output of the image
magick
display program that saving in showfoto creates an "icc profile" of
"sRGB", whatever that might mean. Yet, when I open the file in gimp, it
asks if I want to convert to sRGB format. And whether I say yes or no, I
still get the blue tinge. Is colour management in GTK + kubuntu simply
broken?  Are digikam and firefox / gimp not speaking the same colour
management language?

And the most important question still remains: is there anything I can
do to ensure that photos that I have edited with showfoto end up on the
web in a format that is similar to what I see in digikam -- even for
users of firefox 3.5.5 with default settings?[1]

-- Alastair

Footnotes:
[1]  Pngcrush looked like a promising way to remove colour management
     information from a file, but for me it bails out with a CRC error.


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Op maandag 23 november 2009, schreef Alastair Burt:

With showfoto 0.9.6 your images look different also. Your original has a
colorprofile sRGB D65 and the saved one sRGB D50. These are different
profiles, and may cause the colorcast you notice in firefox. Have a look at
you colormanagement settings in digiKam/showFoto

Caspar.
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[Alastair Burt]

Caspar Maessen wrote:
> Op maandag 23 november 2009, schreef Alastair Burt:
>
> With showfoto 0.9.6 your images look different also. Your original has a
> colorprofile sRGB D65 and the saved one sRGB D50. These are different
> profiles, and may cause the colorcast you notice in firefox. Have a
look at
> you colormanagement settings in digiKam/showFoto

That is interesting information. The whole time, colour management has
been turned off in my digikam and showfoto -- at least according to the tab
in my settings dialogue. I wonder what tool you used to find out the
colour profile of the original. When I examine the original in showfoto
(version 0.10.0), it tells me the photo has icc profile "sRGB
whitepoint: D50". Perhaps, that is where the problem lies?

-- Alastair

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[Marcel Wiesweg]

Please please if you use color management use digikam 1.0!
In certain older version a sRGB profile with a wrong white point was shipped.

Marcel
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Op maandag 23 november 2009, schreef Alastair Burt:

  > I wonder what tool you used to find out the
  > colour profile of the original.

Just the color tab of digiKam/showFoto, but as I said it is version 0.9.6.
Perhaps your problem is what Marcel is pointing at in his mail.

Caspar.
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[Alastair Burt]

Marcel Wiesweg wrote:
> Please please if you use color management use digikam 1.0!
> In certain older version a sRGB profile with a wrong white point was
> shipped.

I did not really want to use colour management, as I do not understand
it and have no idea what any of my devices support. But even with colour
management turned off in digikam/showfoto settings, it seems I am
getting an icc profile added to my files. I briefly looked at digikam
1.0 beta, but there are no precompiled binaries, and my standard kubuntu
system does not have the development files installed to compile it from
scratch.

In the end, I discovered that image magick can patch my problem for the
time being. "convert +profile icc" will remove the profile that showfoto
adds and the resulting files appear normal in firefox and gimp. I will
use that solution until digikam 1.0 goes more mainstream. Thanks to
you guys on the list for helping me track this down.

-- Alastair

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Am Montag, 23. November 2009 20:56:29 schrieb Alastair Burt:

> Marcel Wiesweg wrote:
> > Please please if you use color management use digikam 1.0!
> > In certain older version a sRGB profile with a wrong white point was
> > shipped.
>
> I did not really want to use colour management, as I do not understand
> it and have no idea what any of my devices support. But even with colour
> management turned off in digikam/showfoto settings, it seems I am
> getting an icc profile added to my files. I briefly looked at digikam
> 1.0 beta, but there are no precompiled binaries, and my standard kubuntu
> system does not have the development files installed to compile it from
> scratch.

This bug is somewhat unrelated to colour management. It was fixed over 6
months ago: https://bugs.kde.org/show_bug.cgi?id=189250 

You really should consider to update your installation of digikam. Compiling
it is very easy: cmake .. && make && sudo make install

Tobias
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[Marcel Wiesweg]

> This bug is somewhat unrelated to colour management. It was fixed over 6
> months ago: https://bugs.kde.org/show_bug.cgi?id=189250
>
> You really should consider to update your installation of digikam.
>  Compiling it is very easy: cmake .. && make && sudo make install

The problem is that the bug is fixed but old photos keep the wrong profile
inside them. It really is a severe problem and it's fully our fault. But we
can't change it anymore, we can only tell people to remove the profile as
Alastair explained.
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[sean darcy]

On Sun, Nov 29, 2009 at 9:28 AM, Marcel Wiesweg <[hidden email]> wrote:

>
>> This bug is somewhat unrelated to colour management. It was fixed over 6
>> months ago: https://bugs.kde.org/show_bug.cgi?id=189250
>>
>> You really should consider to update your installation of digikam.
>>  Compiling it is very easy: cmake .. && make && sudo make install
>
> The problem is that the bug is fixed but old photos keep the wrong profile
> inside them. It really is a severe problem and it's fully our fault. But we
> can't change it anymore, we can only tell people to remove the profile as
> Alastair explained.

If we have digikam => 1.0.0-beta1, can we open the old jpeg's and then
save them with the correct profile? If so, can this be set up as a
batch process? It'd be a real pain to do this one-by-one.

sean
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[Marcel Wiesweg]

> If we have digikam => 1.0.0-beta1, can we open the old jpeg's and then
> save them with the correct profile?

No, because digikam will take the profile and use it ;-)

> If so, can this be set up as a
> batch process? It'd be a real pain to do this one-by-one.

There is currently no batch process to change convert or remove color
profiles, though it should be added in the future.
For now, I know of the ImageMagick solution - I hope this is a lossless
operation?? If not we should think of something else.

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[sean darcy]

On Sun, Nov 29, 2009 at 12:40 PM, Marcel Wiesweg <[hidden email]> wrote:

>
>> If we have digikam => 1.0.0-beta1, can we open the old jpeg's and then
>> save them with the correct profile?
>
> No, because digikam will take the profile and use it ;-)
>
>> If so, can this be set up as a
>> batch process? It'd be a real pain to do this one-by-one.
>
> There is currently no batch process to change convert or remove color
> profiles, though it should be added in the future.
> For now, I know of the ImageMagick solution - I hope this is a lossless
> operation?? If not we should think of something else.
>

:( .

I'll go try to figure out the IM solution.

Thanks.

sean
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[Milan Knížek]

Marcel Wiesweg píše v Ne 29. 11. 2009 v 18:40 +0100:
> There is currently no batch process to change convert or remove color
> profiles, though it should be added in the future.
> For now, I know of the ImageMagick solution - I hope this is a lossless
> operation?? If not we should think of something else.
>
For the curiosity, I ran "convert input.jpg +profile icc output.jpg" 400
times in a loop. Well, it seems that even this simple operation re-codes
jpeg since every image was a bit different. The same applies to "mogrify
+profile icc image.jpg".

It may be safer to use e.g. exiftool to remove the ICC profile from
image without recoding:

$ exiftool -ICC_Profile="" image.jpg

I believe exiv2 could do similarly.

Regards,

Milan Knizek
knizek (dot) confy (at) volny (dot) cz
http://www.milan-knizek.net - About linux and photography (Czech
language only)

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[Marcel Wiesweg]

> It may be safer to use e.g. exiftool to remove the ICC profile from
> image without recoding:
>
> $ exiftool -ICC_Profile="" image.jpg

Thanks Milan!
I didn't find an option in exiv2.
So for now, the above command is the official recommendation handle this case.
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