An aspect ratio is a figure that represents the width-to-height ratio of an image. It is the division between width and height of an image.
The most frequent aspect ratios are 4:3 and 16:9 (the later is used in high definition televisions).
Take the aspect ratio 4:3. The first number, 4, means the width of the image, while the second number, 3, indicates the height. In this case means for every four inches the image is wide, it is three inches high.
For example, if we have a screen 6 feet width (1,8 meters) and 4,5 feet high (1,37 meters), the aspect ratio will be 4:3.
The two most common aspect ratios are 4:3 (used in most computers and older televisions) and 16:9 aspect ratio (used in widescreens televisions or films). In the projector specifications we will find which is its native aspect ratio. This aspect ratio is the one designed for that particular projector, it will probably admit other aspect ratio although there will be a quality loss.
Given that aspect ratios are never square, to get a square image we will have to colour in black the sides of the image.
If we divide 16 / 9 we will get 1.777777778, why do we not use this number?
We reckon these are some of the reasons:
This is applicable to every aspect ratio.
If we divide width by height, we will get the aspect ratio for that particular device.
|Resolution||We divide both numbers||We will get the aspect ratio|
|640x480||640 / 480 = 1.3333||4:3 = 1.3333|
|1920x1080||1920 / 1080 = 1,7777||16:9 = 1,7777|