[SOLVED] libpng warning: iCCP: known incorrect sRGB profile drive me nuts

mrjj

Well its the profile.
"it's because libpng 1.6 does more checking of the pngs, and one or more of the png files used has an old sRGB profile"

But how can it be old when its a photoshop 2015 ?
No of the other tools consider the profile old.

Its a strange warning as nothing is wrong with the profile and
its the std one.

Reading here
http://www.imagemagick.org/discourse-server/viewtopic.php?t=25880

it says
"The feature for skipping the sRGB profile-checking was added to libpng-1.6.12"

So is there any way I could enable that for Qt ?

SGaist

You'd have to rebuild the png plugin after "fixing" the sources to not do the check

mrjj

@SGaist
Which means I would have to have VSxxx excact version , which I do not so I am going to try the libpng forums to find out what exactly it thinks is wrong with the embedded color profile. If only it would also print the file name....

Thank you

SGaist

Why ? You already have the compiler matching your Qt version, no need of more for testing the png plugin

mrjj

@SGaist
Hi
But my Qt Creator is compiled with VS so I assumed that compiling a new png plugin with minGW is a no go ? (as in wont work)

SGaist

The Qt version used for Qt Creator and the one you use for your application doesn't need to match unless you are building a Qt Creator plugin but in the case of your tests to disable this warning, you don't need to build a Qt Creator plugin.

mrjj

@SGaist
Ahh, now I understand you. (i think)
So you say I can create a new png plugin
and then load that in my application ?
I guess I have to put it in build folder/plugins for app to load the modified one?

SGaist

IIRC, the plugin will be replaced directly in your Qt installation once built

mrjj

@SGaist
As in
D:\Qt\Tools\QtCreator\bin\plugins\imageformats
hmm
http://doc.qt.io/qt-5/qtimageformats-index.html

dont list PNG.

So its not a plugin but sort of build in ?

SGaist

No, as in D:\Qt\5.5\MinGW\plugins\imageformats

Don't mix the Qt you use with Qt Creator.

PNG support is in qtbase (it's in the list on the second line of the first paragraph). But now that you mentioned it, you're right: it's builtin.

mrjj

@SGaist
Ahh, of cause . Creator is Vs but mingw need its own version.
Hmm I getting blind, as I see no mention of qtbase but now i know.
Maybe I should try it on linux where all will be gcc. (I hope)

Thank you for your time.

SGaist

The Qt Gui module is in qtbase.

But again, it has nothing to do with Qt Creator, to make your tests with pngs, you'll have to build qtbase (only qtbase, no need for the rest) so it will be a new Qt version + corresponding Kit for Qt Creator

mrjj

@SGaist
Ah. That way.
Is there anywhere I can see which modules are part of what etc? like an overview.
So qtbase.pro files must the one Im looking for.

I assume getting the one from
git://gitorious.org/qt/qtbase.git.

could work.

Thank you for all the info.

mrjj

well it seems libpng follow standard and
photoshop is not strict enough, so I just have to live with it or
strip the profile completely.

"
Error detection in some chunks has improved; in particular the iCCP chunk
reader now does pretty complete validation of the basic format. Some bad
profiles that were previously accepted are now rejected, in particular the
very old broken Microsoft/HP sRGB profile. The PNG spec requirement that
only grayscale profiles may appear in images with color type 0 or 4 and that
even if the image only contains gray pixels, only RGB profiles may appear
in images with color type 2, 3, or 6, is now enforced. The sRGB chunk
is allowed to appear in images with any color type.
"

aghilpro

@mrjj This Warning is about PNG formats and Qt, Irrelevant to @ztono code. Read more about PNG (Portable Network Graphics) https://en.wikipedia.org/wiki/Portable_Network_Graphics

PNG has many Formats some old, some not standard for Qt. see more History_and_development You need to use Standard format in Qt.

Answer To Your Problem: https://stackoverflow.com/questions/43374187/qt-open-a-jpg-file-with-warning-image-format-not-supported

mrjj

@aghilpro
Actually it turn out it was the color profile that photoshop put in the png file and
libpng didn't like it. Seems to have vanish in later Qt versions.

__d4ve__

Open with -> Photoshop -> File -> Save for web... -> Save..

seyed

As a quick solution, you can fix that image using some optimisation utilities.
On the MacOS, I successfully solved this problem using the ImageOptim.
On other platforms, there is some similar tools such as the Trimage for Linux and the pinga for Windows, but I didn't test these.