Image resolution on browers (Safari, Chrome)

Hello everyone,

I recently bought a new Macbook Pro 13" retina, and really pleased with it. I noticed images are displayed not according to their original size. I usually upload images at 1920pxl on an aviation site, using the default display settings. Though, when displayed, the image looks much bigger (a 1920pxl should fit a 2560pxl display). I found this issue on both Safari and Chrome. I'm attaching an image as example.

Hope I was as clear as possible, thanks in advance.

Lorenzo