Images won't fill up the entire width

Hi everybody,

For some reason, images won’t fill up the entire width of the column on my website :

The original image size is 1920x1275px but as it is displayed in posts or on the front page, it gets shrunk down and I can’t figure why.

Is there something I am missing ?

Thanks in advance for your time.


I see that you have already figured out everything your self as all images on your website are displayed exactly like they should.