Long story short, all images in browser are displayed wierd.
Here is the comparison between browser and window's image viewer on the same image (downloaded) :https://i.stack.imgur.com/xkiNl.jpg
This problem started on chrome, so I installed opera because the problem was persistent and found no answer to my question. Now after a while the problem started to appear on opera too. I'm baffled why this suddenly happened and why is persistent even after windows restart...
I have no idea why this would happen, so maybe you can help me.
Chrome on my machine started doing this around the same time. After some digging around and trial and error I think it's having issues with some monitor colour profiles.
I did manage to get a workaround in the end by changing the colour profile of the monitor to sRGB IEC61966-2.1. In Windows 8.1:
Control Panel > Color Management then select your monitor. Make sure Use my settings for this device is checked. Add the sRGB IEC61966-2.1 profile and set it to default
Restart Chrome and you should be able to see the proper amount of colours again.