On July 9th the ongoing debate between 2K and 4K digital cinema picture resolution took an interesting turn when an unexpected player entered the fray. At VidCon 2010, a conference for online video professionals, came to a close, YouTube announced that they would begin supporting and streaming videos shot in 4K. (And you thought the popular website was only good for short clips of cats riding vacuum cleaners).

Okay granted, this news doesn’t really advance the discussion of digital cinema so much as it raises the awareness of projected image resolution to many industry outsiders who had never given it much thought before. YouTube’s blog post announcing the support of 4K is a perfect example of how the topic is being discussed by the public at large:

To give some perspective on the size of 4K, the ideal screen size for a 4K video is 25 feet; IMAX movies are projected through two 2k resolution projectors.

It was only in December of 2009 that YouTube announced they would allow for 1080p video content to be uploaded and streamed. Less then a year later they are increasing the resolution of the videos they’ll accept by four times to 4096 x 2304 pixels. As a comparison, Sony’s SRX-R320 digital cinema projector has a native resolution of 4096 x 2160 pixels.

Now let’s try and be realistic about who can actually view a YouTube clip in 4K. Most monitors aren’t even 1080p HD let alone capable of 4K. I’m not even sure a television exists that can display 4K, (though no doubt someone will likely correct me wrong in the comments). YouTube probably put it best in stating:

Because 4K represents the highest quality of video available, there are a few limitations that you should be aware of. First off, video cameras that shoot in 4K aren’t cheap, and projectors that show videos in 4K are typically the size of a small refrigerator. And, as we mentioned, watching these videos on YouTube will require super-fast broadband.

Effectively YouTube can now accept videos created by a limited number of professionals and stream it to the small handful of people in the world who have an Internet connection fast enough to download it and probably the most expensive playback device on the market today.

And this isn’t even touching on the compression issues. Because the video will be traveling via the Internet it will need to be compressed and thus 4K video will likely be playing back at a low bit rate, not the 250 Mbps max the DCI spec calls for. So it will be a while before theatre owners have to worry about moviegoers staying home to watch content on YouTube that’s comparable to digital cinema.

If you want to get a look at what 4K videos look like on the web, YouTube has been kind enough to create a special playlist with content shot in 4K.