Why is it called 4k video?

[Hellis 0]

I just read the specs for the new GoPro and noticed how the name of videosizes has changed.

720 is video with 1280x720 pixels
1080 is 1920x1080
Then
2.7k is 2704x1520, why is it not called 1520?
4k is 3840x2160, why is it not called 2160?

Is it just marketing, or is there a real reason why the industry all of the sudden changed to use the "large" number as the name of the videosize?

[verdi 2]

because it's 4 times 1080 ;-)

[DSE 3]

Hellis

I just read the specs for the new GoPro and noticed how the name of videosizes has changed.

720 is video with 1280x720 pixels
1080 is 1920x1080
Then
2.7k is 2704x1520, why is it not called 1520?
4k is 3840x2160, why is it not called 2160?

Is it just marketing, or is there a real reason why the industry all of the sudden changed to use the "large" number as the name of the videosize?

Almost but not quite.
4K can be UHD or true 4K.
4096 x 2160 @ 1:9 aspect ratio is indeed 4K
3840 x 2160 is UHD, which is 4X the resolution of "true HD."

Because aspect ratios are variable, the horizontal resolution is what matters "most" in 4K, whereas in 1080 and 720, the aspect ratio is virtually always 16:9.

Some love to quibble over the couple of hundred difference in pixels. Measurebators will always be into the numbers vs the actuality.
I hope that helps answer the question?

[Arvoitus 1]

4k refers to the horizontal resolution, 3840 is almost 4000 (4k).

Your rights end where my feelings begin.

[mccordia 73]

A4K (Almost4K) doesnt sound as cool, so they left out the A

But then using Ultra4K to define a resolution lower than full 4K res is even weirder if you take the actual definition of Ultra being 'extreme/beyond'.

JC
FlyLikeBrick
I'm an Athlete?

[JWest 0]

It has to do with ... just watch this.

http://youtu.be/kIf9h2Gkm_U?t=1m26s