What is the Aspect Ratio?
The term aspect ratio was initially used in motion pictures, indicating how wide the picture was in relation to its height. Movies were initially in 4:3 aspect ratio, and this carried over into television and early computer displays. Motion picture aspect ratio changed much more quickly to a wider screen, which meant that when movies were shown on TV they had to be cropped or the image manipulated in other ways to fit the TV screen.
As display technology improved, TV and monitor manufacturers began to move toward widescreen displays as well. Originally "widescreen" referred to anything wider than the typical 4:3 display, but it quickly came to mean a 16:10 ratio and later 16:9. Nowadays, nearly all computer monitors and TVs are only available in widescreen, and TV broadcasts and web pages have adapted to match.
Until 2010, 16:10 was the most popular aspect ratio for widescreen computer displays. However, with the rise in popularity of high definition televisions, which were using high definition resolutions such as 720p and 1080p and made these terms synonyms with high-definition, 16:9 has become the high-definition standard aspect ratio.
Depending on the aspect ratio of your display, you can use only resolutions that are specific to its width and height. Some of the most common resolutions that can be used for each aspect ratio are the following:
4:3 aspect ratio resolutions: 640×480, 800×600, 960×720, 1024×768, 1280×960, 1400×1050, 1440×1080, 1600×1200, 1856×1392, 1920×1440, and 2048×1536.
16:10 aspect ratio resolutions: 1280×800, 1440×900, 1680×1050, 1920×1200 and 2560×1600.
16:9 aspect ratio resolutions: 1024×576, 1152×648, 1280×720 (HD), 1366×768, 1600×900, 1920×1080 (FHD), 2560×1440, 3840×2160 (4K), and 7680 x 4320 (8K).
Is there a relation between aspect ratio and display orientation?
The display orientation refers to how you look at a screen: the most common screen orientations used are landscape and portrait. Landscape orientation means that the width of the screen is larger than its height, while portrait orientation means the opposite.
Most large screens such as the ones we use on our computers, laptops, or TVs use landscape orientation. Smaller screens such as the ones on our smartphones are usually used in portrait mode, but because their size allows you to easily rotate them, they can also be used in landscape mode.
The aspect ratio of a screen defines the ratio of its longer side to its shorter side. Consequently, that means that the aspect ratio of a screen tells you the ratio of the width to height when you look at it in landscape mode. The aspect ratio is not used to describe screens (or any rectangular shapes) in portrait mode.
In other words, you could say that an aspect ratio of 16x9 is the same as 9x16, but the latter is not an accepted form of referring to aspect ratio.
However, you can refer to screen resolution in both ways. For example, a resolution of 1920x1080 pixels is the same as 1080x1920 pixels; it is just that the orientation differs.
How does the size of the screen affect resolution?
Although a 4:3 TV's display can be adjusted to show black bars at the top and bottom of the screen while a widescreen movie or show is being displayed, this does not make sense with a monitor, so Windows does not even offer you the widescreen display as a choice. You can watch movies with black bars as if you were watching a TV screen, but this is done by your media player.
The most important thing is not the monitor size, but its ability to display higher resolution images. The higher you set the resolution, the smaller the images on the screen are, and there comes a point at which the text on the screen becomes so small it is not readable. On a larger monitor it is possible to push the resolution very high indeed, but if that monitor's pixel density is not up to par, you won't get the maximum possible resolution before the image becomes unreadable. In many cases, the monitor does not display anything at all if you tell Windows to use a resolution that the monitor cannot handle. In other words, do not expect miracles out of a cheap monitor. When it comes to high-definition displays, you definitely get what you pay for.
Pixel Aspect Ratio
A pixel is a smallest unit in an image.
PIXEL can be rectangular or square.
Pixel Aspect Ratio = Length of pixel ÷ Breadth of pixel
It is notated by the form a:b
E.g. 1.78:1, 1.33:1, etc. Sometimes, people drop the ‘:1’ for brevity. It can also be less than one, as in 0.9 for NTSC 4:3.
Why is the pixel aspect ratio important?
The pixel aspect ratio changes the size of an image, and this can be illustrated with an example.
If an image with the resolution 720×576 has a pixel aspect ratio of 1.0 (square pixels), then the size of my image is 720×576.
However, an image with the resolution 720×576 but with a pixel aspect ratio of 1.422:1 (length of the pixel is 1.422 times the breadth) will have a size of:
(720 x 1.422) x 576 = 1024×576
This means that even though the actual pixel count horizontally is only 720, by stretching the pixel a manufacturer can claim it is 1024!
In the above example, it is important to note that the resolution of the image is still 720×576, but the size of the image has changed to 1024×576 – there is no additional detail, just a stretched image.
Squashed or stretched footage has its genesis in the selection of incorrect pixel aspect ratios.
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