The following images contain embedded non-free IEC61966-2.1 colour profile:
$ exiftool icons/scaling.png Profile Copyright : Copyright (c) 1998 Hewlett-Packard Company Profile Description : sRGB IEC61966-2.1
This means that (propriatary?) graphics editor saved image(s) with embedded non-free IEC61966-2.1 colour profile.
IEC61966-2.1 prohibits modification, see http://www.color.org/srgbprofiles.xalter#v2
Non-free ICC profile can be removed using the following command
exiftool -icc_profile"-<=" {IMAGE.png}
or using GIMP (Image --> Mode --> Convert to Color Profile).
Thanks, done in r19931.
Thanks.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/1918