pixel art and render mode, what am i doing wrong?

I have a 16:9 aspect ratio iMac with resolution set to 1920 x1080, and for my game i also use a 16:9 aspect ratio size. I want to use pixel art so its crisp so i set fullscreen mode to "letter box integer scale" yet when i run the game i get black bars. If i use the browser object and set it to go full screen i still get black bars.

The only way i can get the game to cover the screen with crisp graphics (not using fullscreen quality high) is to set full screen mode to "scale outer" and set the canvas size to the window size. This seems to work well for me since the game is designed so the hud and things can handle different screen sizes but i wonder if there is any pitfalls to doing this? I haven't noticed any drop in fps.

Also why won't "letter box integer scale" work as it should, as in fill the screen at this size and aspect ratio?

Thanks.

It seems that you get black bars with a "letter box integer scale" because the resolution of the game is less than the screen resolution.

If I understand you correctly, you should select "letterbox scale" and set sampling to "point".