I saw that Firefox automatically fit too large pictures to the window frame, and that's a fantastic feature Second fantastic feature: Firefox can automatically fit the same way when you zoom in pictures so it will perfectly fit the frame So Firefox seems to have the required features to accomplish what I want to ask for I would like Firefox to automatically open all pictures maximized and that they automatically fit at window resizing Because it's actually the case but only for too large pictures. Too tiny pictures, when you zoom in, they conserve the size and don't resize as you resize the window. And too tiny pictures doesn't open maximized but at 1:1 pixel ratio