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What is the difference between SD, HD, 2k and 4k?

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What is the difference between SD, HD, 2k and 4k?

You will often see smartphone displays, monitors, display cables, projectors, and other display equipments marked like SD, HD, 720, 1080, or 4K. But have you ever wondered what these numbers or resolution means and what is the difference between these numbers?

These numbers denote the resolution or the pixel count of a particular display. An SD display starts at 240p and goes up to 480p. Similarly, a HD display is a 720p or 1080p display. A 2K display has a pixel width that falls in the range of 2000 pixels, hence the name 2K. This nomenclature applies to a 4K display as well. A 4K display has a pixel width in the range of 4000 pixels.

Also Read: 1080i vs 1080p: What’s the difference and which one is better?


Resolutions refer to the total number of pixels present on the display. An SD display has a 240p or 360p or 480p resolution. A 240p resolution means the pixels count of the screen is 352×240. This means that there are 352 pixels in a single vertical line and 240 pixels in a horizontal line. The number of vertical and horizontal lines is also equal to the 352 and 240 in a 240p display. Likewise, a 360p display has a pixel count of 480×360 pixels and a 480p display has a pixel count of 858×480 pixels.

What is the difference between SD, HD, 2k and 4k?
Source: Wikipedia Commons

Jumping to the HD resolution, a 720p display has a resolution or pixel count of 1280×720 with 1280 vertical lines and 720 horizontal lines of pixels. A 1080p display has a resolution of 1920×1080. Both resolutions form the HD display formats. The 720p is referred to as an HD display, while the 1080p display is marketed as a Full HD display.

2K displays have a resolution of 2560×1440 which is often written as 1440p as well. Similarly, a 4K display has a resolution of 3860×2160 which is also written as 2160p. The resolution of a display is a key factor in deciding the picture quality. Hence, the better the resolution, the better will be the picture quality.

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Picture Quality

Better resolution translates to better picture quality most of the time. A 360p image will be much sharper than a 240p image. Similarly, a 4K image will be sharper than a 1080p image because of the high pixel count.

But picture quality depends on a number of factors such as contrast, dynamic range, saturation, colour accuracy and plenty of other factors including resolution. A 720p picture can look better than a 1080p picture because of better calibration of all the factors.

What is the difference between SD, HD, 2k and 4k?

While this phenomenon can be true for pictures with close resolutions, but with pictures or videos having resolutions on different ends of resolution scale, the higher resolution wins.

If you are looking for a display or TV I would prefer you to go with a panel with 1080p (Full HD) or above. Choosing a higher resolution panel will also give you the freedom of running or showcasing any lower resolution image.

Also Read: How to prepare photos for the Web?


Akshit Kansal

A BTech student whose interest lies in automobiles, tech, music, coding and badminton.