I have this option checked in the plugin options and my screen resolution is 1280*1024.
When the image to be resized is really big (let´s say 2600 px width) it opens at full screen width as intended, but when it is just 1600px width it displays smaller than the screen width, even at 800px width, which i find too small.
I thought that any bigger image than screen resolution would be resized to fit the full screen but the behaviour is actually a bit strange from page to page. I tried a gallery of only 1600px images but it still displays the images at 800px instead of the screen width.
Maybe i am missing something, any light on this would be welcome!