That’s the way to clearly show the vertical resolution and the type of scanning.

Resolution is the quantity of pixels on the screen. All of the above is the vertical pixel numbers for 16:9 formats:

• 240p = 352 x 240
• 360 p = 480 x 360
• 480p = 858 x 480 — also known as SD
• 720p = 1280 x 720 — the old TVs of this resolution were marked HDready
• 1080p = 1920 x 1080 — FullHD
• 2160p = 3860 x 2160 —Ultra-HD, also known as 4K (that’s a marketing trick)

Now let’s discuss what that little “p” means. “P” stands for progressive scanning. This term comes from old CRT TVs when the picture had to be “scanned” to be drawn. Progressive scanning means that every frame from 60 frames-per-second feed is fully drawn.

There are also formats like 480i, 720i and 1080i. Little “i” means that this is interlaced formats. Interlacing is shown on the picture below:

Interlacing is a process when the odd and even frames of the video get only odd and even lines of the image. For example, on the first frame you see only lines 1,3,5 and so on, but on the second frame you see lines 2,4,6 and so on. That allows to get the video two times less heavy, but it creates “lining” effect that can be seen on the old VHS tapes in the fast moving scenes. Also, it means that the vertical resolution of the image is actually two times less. For example:

• 1080p = 1920 x 1080 pixels
• 1080i = 1920 x 540 pixels

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