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Which is simpler to you as consumer, using the term UHDTV or call it 4K?

About 3.75K?

The audio/video industry has been increasingly complex since the introduction of the home theater concept, and grew excessively complex with digital TV and connectivity. You may be alone if you never had any HDMI or HDCP issues. The higher 4K bandwidth requirements and reinforced content protection of 4K (HDCP 2.2) bring instant obsolescence of perfectly functional home theater equipment including relatively new UHDTVs, most unable to be upgraded by the manufacturer.

As you may know already, a UHDTV has just 3840 horizontal pixels rather than the 4096 pixels of true 4K, a term that originated from the Digital Cinema Initiatives (DCI) standard for motion pictures and commercial theaters projecting them.

Loosely naming “4K” almost all UHDTVs in the market over the past 3 years motivated rumors of lawyers salivating for potential misrepresentation lawsuits filed by people that may claim they are missing 256 horizontal pixels on their new 4K TV.

Although both formats have 2160 pixels in the vertical axis, they differ on the horizontal axis resolution, color space, quantization levels (10, 12 bits per channel), gamma, etc. (details further below).

Source: SONY

Although “K” is a term typically used to express “1000”, the binary digital world uses it to express “1024” and 4K Digital Cinema uses it. 4K is then 4 times 1024 = 4096 pixels of resolution on the horizontal axis of the image.

In strict terms, an Ultra TV device having a lower number of pixels horizontally should not qualify for the use of the term 4K and selling UHDTVs with 3840 pixels had some in the industry concerned about using the term 4K when the set and the image are actually 3.75K based on pixel count and the “1024” binary concept.

My answer to that is (and has been since I got my true 4096-pixels 4K projector 3 years ago): Keep it simple, and move on, people are very accustomed to loosely use the term 4K without counting pixels.


Digital Cinema Initiatives (DCI) 4K standard:

And I quote from the standard document:

"A joint project of seven motion picture studios (Disney, Fox, MGM, Paramount, Sony Pictures Entertainment, Universal, and Warner Bros.), DCI published their specification in 2005....The primary purpose of DCI is to establish uniform specifications for Digital Cinema.."

"The Digital Cinema system shall have the capability to present a theatrical experience that is better than what one could achieve now with a traditional 35mm Answer Print."

"The specification calls for picture encoding using the ISO/IEC 15444-1 "JPEG2000" (.jp2) standard and use of the CIE XYZ color space at 12 bits per component encoded with a 2.6 gamma applied at projection, and audio using the "Broadcast Wave" (.wav) format at 24 bits and 48 kHz or 96 kHz sampling, controlled by an XML-format Composition Playlist, into an MXF-compliant file at a maximum data rate of 250 Mbit/s."

DCI Formats: 2K and 4K. K means 1024 pixels of horizontal resolution.

2K Format: 2048x1080

4K Format: 4096x2160

Aspect Ratio: 1.89 (17:9)

Color Space: 12-bit each per X'Y'Z' channel using the most significant bits of 16-bit words (filled with 4 zeros)

Audio: capacity for up to 16 channels of uncompressed audio at 24 (AES3) bits at 48 kHz or 96 kHz sampling rates, with subtitles. The presentation is required to provide, at a minimum, a 5.1 audio format, (Left, Center, Right, Low Frequency Effects, Left Surround and Right Surround).

Frame Speed: 2K: could be 24fps or 48fps (12-bit DCDM), 4K could be 24fps only

Spatial Resolution Conversion (as per DCI standard): "The projector is required to display either a native resolution of 4096x2160 or 2048x1080. If the projector's native resolution is 4096x2160, and the incoming spatial resolution of the content is 2048x1080, then the projection system is required to perform the up-conversion of 2048x1080 content to 4096x2160. All spatial conversions are required to be done at an exact ratio of 2:1 in each axis, i.e., a projector with a horizontal pixel count of slightly higher than the image container is required to not convert the projected image beyond the image container to fill the array, nor is an image to be converted to something less than the 4096x2160 or 2048x1080 image container size.

Should electronic image resizing or scaling be used to support a constant height projection or constant width projection theater environment, then it is required that the image resizing or scaling does not introduce visible image artifacts."

Ultra-HDTV as defined by the ITU (International Telecommunication Union):

As per ITU-R BT.2020 UHDTV parameters document (August 2012)

Picture aspect ratio: 16x9

Quantization Levels: 10 and 12 bit per component

Colorimetry: Rec.2020

Frame frequencies (Hz): 24, 30, 60, and (updated to) 120 fps, and also 25 and 50 for other systems/countries.

Scan mode: progressive

Resolutions: 3840x2160 and 7680x4320, also called as 4K and 8K by ITU:

The first level of UHDTV picture levels has the equivalent of about 8 megapixels (3840 x 2160 image system), and the next level comes with the equivalent of about 32 megapixels (7680 x 4320 image system).  As a shorthand way of describing them, they are sometimes called the ‘4K’ and ‘8K’ UHDTV systems.”

Recommended diagonal minimum size of screens: 1.5 meters and larger screens (LSDI) of large venue presentations to "provide viewers with an increased sense of “being there” and increased sense of realness" and "higher spatial/temporal resolution, wider colour gamut, wider dynamic range, etc."


The term 4K has been knowingly and unknowingly used by the industry and by journalism even before any UHDTV set was introduced; it is too late to reverse the misuse of the term now.

The reality is that no consumer UHDTV panel/projector (except Sony’s 4K projectors) has 4096 pixels and a 17:9 aspect-ratio image (the relation between the width and the height of an image).

All UHDTVs inherited the HDTV 16:9 aspect-ratio, doubling up the 1920 horizontal pixels of HD to 3840, and also doubling up the 1080 vertical axis pixels of HD to 2160, reason by which UHDTVs are advertised as having 4 times the (spatial) resolution of HDTVs, and the “4 number” has nothing to do with the “4 number in 4K”, which is another element of confusion.

Over the past 3 years I have written several articles about 4K and UHDTV almost exclusively, and I am glad the industry has relaxed a bit on the naming issue and uses 4K and UHD interchangeably, sometimes both at the same time for the advertised product.

Here is one article that discusses the 4K and UHDTV concepts, and also highlighted on the table below.

Summary of 4K/U-HD/U-HDTV naming conventions (and HDTV)

Although this is the HDTV Magazine we also include true 4K devices, such as the 4K Sony consumer projectors, for example my VPL-VW1100.

Regardless how you prefer to name it, what happens when I project a UHD image with the 4K projector?

Although the projector could upscale the 3840 pixels horizontally to 4096, I typically project the 3840 pixels using the center of the 4096 pixels chip, and the resulting image shows with two thin black pillars of 128 black pixels at each side. Projecting the image this way maintains the 1-to-1 pixel relationship between image source and imager chip of the projector, no scaling takes place.

Several years ago I was reviewing my 4K projector with Sony’s 4K demo content. Some short clips were in true 4K and some in UHD format. Although my theater has a Cinemascope screen, which is also the wide image format I prefer for movie content, I was pleased with the 17:9 aspect-ratio of the few clips that were actually in 4096x2160 4K. The width of the format was in between HDTV and Cinemascope formats.

Not having such 17:9 content any longer do I mind viewing UHD or HD 16:9 content projected with the 17:9 chip? Yes and no. However, there is not much I can do, all UHD content is/will be in 16:9 format (although Cinemascope 2.35:1 and 1.85:1 movies will be letterboxed within the 16:9 image), and consumers will not notice that the resolution of the image is actually 3.75K in terms of horizontal pixel count, and their UHDTVs are also 3.75K.

The resolution naming saga of “4K or UHDTV” is being left behind and the industry is now realizing that although the UHDTVs are 4 times the resolution of HD the better picture quality was not easily detected by consumers, unless they shorten the viewing distance to appreciate the higher pixel density, or increased the panel size much beyond the typical 50+ inch.

Resolution is now becoming a secondary factor on image improvement, new efforts on the industry are coming to UHDTV, such as a) High Dynamic Range (HDR) to show brighter whites further contrasted from the blacker blacks at the same time in the image, b) High Frame Rate (HFR) to provide enhanced smoothness to fast action images, and c) an expanded color gamut beyond the boundaries of HDTV that the human eye is capable to see.

Adding those features to the higher resolution of an UHDTV would produce an image that will be easily detected and admired by consumers.

Unfortunately, those features are not software upgradable, such as HDMI 2.0 and HDCP 2.2 for 4K; your UHDTV may still show UHD content if compliant with the content protection but within the limitations of the TV, smaller color gamut, lower bit depth, standard dynamic range, lower frame rate, etc.

My recommendation is that if you “need” a new TV give the chance to an UHDTV that fits your budget, otherwise wait a bit longer until the features above are implemented.

Posted by Rodolfo La Maestra, May 6, 2015 9:19 AM

More in Category: 4K (Ultra HD)

About Rodolfo La Maestra

Rodolfo La Maestra is the Senior Technical Director of UHDTV Magazine and HDTV Magazine and participated in the HDTV vision since the late 1980's. In the late 1990's, he began tracking and reviewing HDTV consumer equipment, and authored the annual HDTV Technology Review report, tutorials, and educative articles for HDTV Magazine, DVDetc and HDTVetc  magazines, Veritas et Visus Newsletter, Display Search, and served as technical consultant/editor for the "Reference Guide" and the "HDTV Glossary of Terms" for HDTVetc and HDTV Magazines.  In 2004, he began recording a weekly HDTV technology program for MD Cable television, which by 2006 reached the rating of second most viewed.

Rodolfo's background encompasses Electronic Engineering, Computer Science, and Audio and Video Electronics, with over 4,700 hours of professional training, a BS in Computer and Information Systems, and thirty+ professional and post-graduate certifications, some from MIT, American, and George Washington Universities.  Rodolfo was also Computer Science professor in five institutions between 1966-1973 in Argentina, regarding IBM, Burroughs, and Honeywell mainframe computers.  After 38 years of computer systems career, Rodolfo retired in 2003 as Chief of Systems Development from the Inter-American Development Bank directing sixty+ software-development computer professionals, supporting member countries in north/central/south America.

In parallel, from 1998 he helped the public with his other career of audio/video electronics, which started with hi-end audio in the early 60’s and merged with Home Theater video, multichannel audio
, HD, 3D and UHDTV. When HDTV started airing in November 1998, and later followed by 3DTV and 4K UHDTV, he realized that the technology as implemented would overwhelm consumers due to its complexity, and it certainly does even today, and launched his mission of educating and helping consumers understand the complexity, the challenge, and the beauty of the technology pursuing better sound and image, so the public learn to appreciate it not just as another television.