Trivia: Aspect Ratios

[Kedirekin]

Sometimes a person has odd trains of thought as they lay awake at night.

We're all familiar with 4:3 and 16:9.

Have you noticed that 4^2 = 16, 3^2 = 9? Odd coincidence, or is there some meaning behind it?

I managed to find this on the net:from Projection Screen Aspect Ratio (http://www.fordav.com/publications/cb12.pdf)

The real origin of the 3:4 aspect ratio had to do with the size of the negative in 35mm movie film after you subtracted for the perforations needed to pull it through a projector.

A fairly interesting read, by the way.


The only information I can find for 16:9 (or any widescreen format) is that it's a better fit for the human visual system. A google search is pretty useless as it turns up a thousand links for TVs and projectors.

Does anyone have any insight on the origin of the 16:9 (1.778:1) aspect ratio? Is there any reason it's the squares of 4:3? Why didn't they choose The Golden Mean (~1.618:1)?

[mpucoder]

Resizing, which is necessary to accomodate the 2 ratios, works best and is easiest to get working in real time if the ratio is a simple integer ratio. Can you think of anything simpler than 3/4 (or 4/3) that results in a usable widescreen DAR?

[hakko504]

Originally posted by mpucoder
Resizing, which is necessary to accomodate the 2 ratios, works best and is easiest to get working in real time if the ratio is a simple integer ratio. Can you think of anything simpler than 3/4 (or 4/3) that results in a usable widescreen DAR? 5:3, 6:3, 7:3 ...

Seriously, I think 16:9 on TV was chosen because of the large number of 1.85:1 movies available and because it's quite close to 1.77:1 which is 16:9. And converting between 16:9 and 4:3 is (as you said) just a matter of removing 1 line in 4, either horizontally or vertically.

As a side note I can mention that the only other predefined aspect ratio in MPEG-2 (not DVD!) is 20:9, a ratio that is defined as (5/4)*(16/9)...