How to avoid a "libpng warning" in runtime UI?

When loading a png file in the WinCC OA Ui sometimes one of the following warnings can occur.

WCCOAui      (<num>), <TIMESTAMP>, SYS,  WARNING,    54, Unexpected state, Qt, libpng warning: iCCP: profile 'ICC Profile': 'CMYK': invalid ICC profile color space

WCCOAui (<num>), <TIMESTAMP> SYS, WARNING, 54, Unexpected state, Qt, libpng warning: iCCP: known incorrect sRGB profile

Those warnings can occur in WinCC OA since 3.14 if a png files is loaded with an RGB profile/ICCP chunk defined as "deprecated".
WinCC OA  is using version 1.6 of the standard libpng as a 3rd party component, within this version of libpng these warnings have been implemented.

Basically you can just choose to ignore those warnings, nothing will happen.

Please note: The programs mentioned below are not part of the WinCC OA installation and have to be downloaded separately from their respective sites.

How to identify the relevant pngs?
There are several programs available to identify the png files, e.g. PNGcrush.
The command line option identify <filename>.png or *.png returns the information which png files are saved with the problematic profile.

How to remove the profile so no warning will be displayed?
With the program Gimp the profile can be changed to a new/better one with the option: Image > Mode > Assign Color Profile.

Modifying the png profile is also possible with the ImageMagicks "mogrify" command.
If the program is started at command line with mogrify *.png all png file in the parent working directory are modified.

Info: All png files included in the WinCC OA version have already been updated to avoid the warnings.

Will there be a loss of quality?
No, if you just strip the color profile e.g. with the mogrify command there will be absolutely no loss in quality.
If you include a new, better suited profile for your targeted hardware you might even experience an increase in quality as the colors will be more lifelike.