Common display resolutions are 144p, 240p, 360p, 480p, 720p, 1080p, 1440p, and 2160p. For example, these are the resolutions that YouTube offers. These are somewhat odd numbers and I cannot find a pattern. I tried searching but could not find the reason why these resolutions were chosen and became standards.
This query is different from this one which inquires about physical screen sizes but it is similar in spirit.
Does anybody know why common display resolutions are the way they are?
16:9 Aspect Ratio
The pattern you're referring to is the 16:9 aspect ratio. @Worthwelle's comment is correct 16:9 replaced 4:3 aspect ratio.
16:9 (1.77:1) (16:9 = 42:32) is an aspect ratio with a width of 16 units and height of 9. Since 2010 it has become the most common aspect ratio for televisions and computer monitors, and is also the international standard format of HDTV, Full HD, non-HD digital television and analog widescreen television. This has replaced the old 4:3 aspect ratio.
The reason why the aspect ratio has become the standard can also be attributed to the DVD format.
16:9 is the only widescreen aspect ratio natively supported by the DVD format. Anamorphic DVD transfers store the information as 5:4 (PAL) or 3:2 (NTSC) square pixels, which is set to expand to either 16:9 or 4:3, which the television or video player handles. For example, a PAL DVD with a full frame image may contain a video resolution of 720×576 (5:4 ratio), but a video player software will stretch this to 1024×576 square pixels with a 16:9 flag in order to recreate the correct aspect ratio.
DVD producers can also choose to show even wider ratios such as 1.85:1 and 2.39:1[a] within the 16:9 DVD frame by hard matting or adding black bars within the image itself. Some films which were made in a 1.85:1 aspect ratio, such as the U.S.-Italian co-production Man of La Mancha and Kenneth Branagh's Much Ado About Nothing, fit quite comfortably onto a 1.77:1 HDTV screen and have been issued as an enhanced version on DVD without the black bars. Many digital video cameras have the capability to record in 16:9.
List of standardised 16:9 resolutions
These are somewhat odd numbers and I cannot find a pattern.
They are not actually random but based on actual industry standards. Low-definition defines anything that is below Standard-definition. Standard-definition and Enhanced-definition take care of resolutions below 576p and below. While High-definition and Ultra High-definition take cares of resolutions between 720p and 8k. In all cases, we are actually talking about television standards, but the same standards are applicable to the resolution on a computer monitor.
Low-definition television (LDTV) refers to television systems that have a lower screen resolution than standard-definition television systems. The term is usually used in reference to digital television, in particular when broadcasting at the same (or similar) resolution as low-definition analog TV systems. Mobile DTV systems usually transmit in low definition, as do all slow-scan TV systems.
Standard-definition television (SDTV or SD) is a television system which uses a resolution that is not considered to be either high or enhanced definition. The two common SDTV signal types are 576i, with 576 interlaced lines of resolution, derived from the European-developed PAL and SECAM systems; 480i based on the American NTSC system. SDTV and high-definition television (HDTV) are the two categories of display formats for digital television (DTV) transmissions.
Standard-definition television
and
Enhanced-definition television or extended-definition television (EDTV) is an American Consumer Electronics Association (CEA) marketing shorthand term for certain digital television (DTV) formats and devices. Specifically, this term defines formats that deliver a picture superior to that of standard-definition television (SDTV) but not as detailed as high-definition television (HDTV).
Enhanced-definition television
High-definition television (HDTV) is a television system providing an image resolution that is of substantially higher resolution than that of standard-definition television. This can be either analog or digital. HDTV is the current standard video format used in most broadcasts: terrestrial broadcast television, cable television, satellite television, Blu-rays, and streaming video.
Ultra-high-definition television (also known as Ultra HD television, Ultra HD, UHDTV, UHD, and Super Hi-Vision) today includes 4K UHD and 8K UHD, which are two digital video formats with an aspect ratio of 16:9. These were first proposed by NHK Science & Technology Research Laboratories and later defined and approved by the International Telecommunication Union (ITU).
Ultra-high-definition television
In most cases, the standards used by the television industry were defined by research, industry or consumer groups. In cases like PAL or NTSC they were chosen by the respective industry groups in the applicable region. Due to the respective choice to implement either NTSC or PAL drove future changes resolution standards.
In the case of an aspect ratio of a given resolution standard is was based on actual science.
The eye's perception of display resolution can be affected by a number of factors – see image resolution and optical resolution. One factor is the display screen's rectangular shape, which is expressed as the ratio of the physical picture width to the physical picture height. This is known as the aspect ratio. A screen's physical aspect ratio and the individual pixels' aspect ratio may not necessarily be the same. An array of 1280 × 720 on a 16:9 display has square pixels, but an array of 1024 × 768 on a 16:9 display has oblong pixels.
An example of pixel shape affecting "resolution" or perceived sharpness: displaying more information in a smaller area using a higher resolution makes the image much clearer or "sharper". However, most recent screen technologies are fixed at a certain resolution; making the resolution lower on these kinds of screens will greatly decrease sharpness, as an interpolation process is used to "fix" the non-native resolution input into the display's native resolution output.
IBM, NEC Home Electronics, and the Video Electronics Standards Association (VESA) also had an influence on what a given resolution would be defined as. While broadcast television had a huge influence, every standard resolution has it's own computer display standard also.
