# How does image resolution change(process involved in calculation), when a screen on phone is rotated?

What is the process involved in calculating the resolution of image to be displayed when the screen of my phone(android) is rotated? My screen resolution is 1920x1080. It displays some videos only in the center while top and bottom of the video are blacked(when phone is held vertical), where as full screen video is shown when phone is held in horizontal position.

• I don't quite understand. What's the problem, or what are you trying to achieve? – Dan Hulme Feb 9 '18 at 8:29
• when I am using phone to watch a video it plays in full screen (1920x1080), but when I tilt it(rotate) the video will be played only in part of the screen, the rest of the areas of screen is black. I wanted to know whether the resolution of image(video) is changed to achieve this! If so how does this happen. Think in terms of aspect ratio or some thing like that – Charan K Feb 9 '18 at 16:08

newHeight = 1080 * (1080 / 1920)

newHeight = 1080 * (9 / 16)