Is 4k the same as UHD or not?
4k is “almost” the same as UHD, but they don’t represent the same technologies, and the terms 4K and UHD can easily be misunderstood. From the consumer’s point of view, 4K and UHD are more or less the same thing.
The technical differences behind these names aren’t notable, if we only view it from the perspective of the resolution. It is important to know a little about the ins and outs of these labels, in order not to misunderstand some specifications of a product, in this case a TV.
What is 4K?
We talked a few months ago about that in this article .
4K is a professional standard used mainly in the film industry . The term 4K comes from DCI – Digital Cinema Initiatives, a consortium of major production studios, which have standardized the specifications for the production and broadcasting of high-resolution content.
In this case, 4K means 4096 x 2160 pixels, exactly 4 times above the previous 2K, of 2048 x 1080 pixels. So 4K is a little more than 4000 pixels, i.e. 4096 as we are talking about digital image. 4K is not just a resolution; the standard also defines how the material is encoded. A 4K stream is compressed using the JPEG2000 codec, and may have a bit rate of about 250 Mbps and a color depth of 12 bits.
Then what is UHD?
UHD is the next step from Full HD, also known as Ultra HD. Full HD is rather a marketing tool, because in the real world we all use the specific resolution, 1920 x 1080 pixels.
As a resolution, UHD is thus 4 times Full HD, i.e. 3840 x 2160 pixels. For this reason, almost all UHD TV panels and monitors have this resolution, slightly less than the actual 4K standard.
As for UHD content there is a lot of ambiguity at present, because there aren’t any clear specifications about how this content is encoded, or what codecs and bitrates are being used. UHD content therefore refers only to the resolution mentioned above and that's it for the time being.
Why not 2160p?
If until now 1080p was used quite a lot to refer to TVs or monitors with 1080p pixel resolution vertically, why isn’t 2160p used now?
The reason will seem funny: if 1080 was somewhat easier to say/utter in English as well as many other languages, 2160 doesn’t sound that great and it’s harder to say.
Even if 2160 would be more accurate, 4K and UHD sound much better in the marketing campaigns of TV manufacturers. It is rather late to start using 2160, because 4K and UHD have become synonymous with the new generation of TVs.
After all what is the problem with UHD?
UHD in itself hasn't got any major issue, but the term is problematic.
There is another standard which has a resolution of 7680 × 4320 pixels, also derived from 3840 x 2160 and also called UHD. It would be natural for the latter to be called Quad Ultra HD, but currently there are not many devices that record and play at this resolution, and of course they are inaccessible technologies for the regular user for the time being.
If we are to speak about the future we assume that 4K UHD and 8K UHD will be used at that time, just as now we already use the 4K UHD term/label for certain products and services.
After all it is quite accurate to use 4K as well as UHD. If the TV and display manufacturers have adopted it as a general term for this standard, then why not use it? The standard for display will be preserved in this way.
All that’s left is the issue of content. Here the content improperly referred to as UHD will be in a large variety of formats and codecs, particularly because it will be mainly distributed via Internet.
For the 4K content, it is quite easy to take into account that a professional camera filming 4K will have a bit rate of 250 Mbps and will use a certain codec, in the case of UHD it just stays at 3840 x 2160 pixels resolution.