How to tell a browser not to resize image

When an image is opened on 4chan.org, it is not automatically res开发者_JAVA技巧ized by my browser (Chrome). How is this done?

There is nothing in the link to a .jpg file in 4chan.org that will cause or prevent resizing. Chrome resizes large images to fit the browser window initially, and then you can click to make it full size. There are no native options to change this, but there are several extensions available for changing this behavior. Maybe you have one of these that is site specific?