How to re-size images for bigger screens?

Is there a way I can increase the size of the images in the posts, for bigger screens?
Another problem that I have noticed in the case of bigger screens( around 1920 x 1080) is that images with captions tend to shift more towards the left, even though I click the center align option.
Also, I have noticed that for bigger screens, the posts on the homepage shift towards the left,leaving a huge gap on the right between the post and the content sidebar.
Any help would be much appreciated.
I can’t find the attach file option, so I am adding the link to a screenshot: http://www.megafileupload.com/en/file/543890/Screenshot-of-captioned-image-moving-left-in-1920-x1080-screen-jpg.html