I just post this in case someone can explain this to me, and hoping this is also usefull to other people:
I've been experiencing some color issue with EOG and Firefox, that where showing a green tint in lots of images. I supposed the issue was with GNOME, and Firefox somehow using the GNOME settings ended up exposing the same bug. It turns out it was otherwise: (from support.mozilla.org):
This can be caused by a problem with the color profile for your display monitor or color profiles embedded in images.
You can disable color management to test that.
You can set the pref gfx.color_management.mode to 0 on the about:config page to disable Color Management.
You need to close and restart Firefox or maybe even reboot the computer to make the change effective.
See also http://kb.mozillazine.org/about%3Aconfig
Go to answer 7
simply go to "about:config" in the firefox addresss bar. Search "color". Doubleclick on the gfx.color_management.mode option and set the value to 3. Then restart firefox.
Go to answer 8
Turns out doing this, not only fixed my Firefox, but also color settings on EOG. Hope this is usefull to others, and... any idea why this happened?