Garo
Boy Wonder
Resolution is a pretty big deal in the modern display world. Or, at least, it's a big deal to consumers. In the past 25 years or so, video technology has been scaling upward rapidly. Standard definition video (usually 640x480) quickly fell by the wayside in the tumultuous wake of high definition video's arrival (typically 1920x1080). High definition is still the standard - it's what televisions use, as it's a convenient standard for pixel density and aspect ratio (16:9 or 1.78:1), and as a result is what most people view content in, be it broadcast television, movies on home media, or video games.
But then in the mid-2000s came the advent of a glorious thing called digital cinema. Digital cinema is the latest and greatest effort to replicate the behavior of traditional celluloid film stock solely through digital technology. Digital video was the first such attempt, but fell woefully short of the mark; it's not even a contest between the visual fidelity of 35mm film stock and digital video (even HD video!). Digital cinema, however, was much, much closer to the mark. It used a gridded array of photosites to capture light and convert it to pixels, which was stored in a compressed file on a flash memory magazine. The biggest obstacle to this technology? Data rates.
Capturing digital cinema was an effort that consumed a lot of data. It wasn't really until the advent of the RED Digital Cinema Camera Company that an adequate system of compression for digital cinema made the technology cheap and effective enough. Once it did, however, film began to fall by the wayside. While the initial digital cinema cameras shot at a resolution designated as 2K (which, despite the name sounding about twice as good as 1080p [since 2K = 2000 ~ 2 x 1080], was actually only marginally better; 2K was a designation referring to a resolution most commonly of 2048x1080. It was an aspect ratio of 1.91:1 rather than HD videos 16:9, as most filmmakers would use a 2.39:1 extraction of the raw image to yield a final resolution of 2048x858 for an anamorphic widescreen render. Either way; not much better than the 1920x1080 resolution of HD video), it very quickly upgraded to the impressive sounding 4K.
4K, however, is a lie.
While technically, most cameras today that capture at a 4K resolution are outputting a 4096x2160 (again, 1.91:1 aspect ratio that is generally extracted to a different ratio; the larger capture aspect ratio allows editors to adjust the frame slightly during post), it's not *true* 4K video capture. The sensors use color filters in order to capture light in such a way that enables for greater compression and higher resolutions than they could achieve otherwise. The RED Mysterium-X sensor, which is the brain of the RED EPIC camera that is so widely loved, uses a Bayer color filter array. What this does is rather than have each photosite in the sensor correspond to a single pixel, it splits the incoming light into its component RGB channels. Half of the available photosites capture green channel light information, and then a quarter each capture the red and blue channels (this is because green channel information is more closely tied to luma or brightness, which our eyes detect better than pure color). It then interpolates the color of pixels based on this segmented color data in a process called "Debayering."
So that 4K resolution image isn't true, 1:1 4K capture. It's actually splitting the color of that light and creating pixels.
To make matters worse, resolution is pretty irrelevant in the grand scheme of things. Most modern displays are not capable of 4K display resolution, but rather adhere to the HD video standard. As such, broadcasts are almost always in the 1920x1080 resolution, so a 4K-capable display is still handicapped by the HD video broadcasts. It might upscale that broadcast, but that's even more interpolation than the Bayered video capture. The only place you're liable to actually see a 4K display is in a theater.
TL;DR? True 4K capture isn't currently feasible, and nearly all displays that you see are actually HD video displays (1920x1080) even despite the faux 4K capture. The companies who market these cameras and display technologies are slightly deceiving customers with the naming of these things; despite HD video being 1080p, which is drawn from the vertical length of the resolution (1920x1080), they named 2K and 4K for the horizontal length of the resolution (2048x1080 and 4096x2160). It's misleading even if it were true 1:1 4K capture.
So with all this in mind, what's all the hubbub about 4K exactly?
Well... it's tremendously useful. Even the Bayered 4K capture is better than 2K and HD video by a significant margin; it might not perfectly match the quality of 35mm film (for a variety of reasons I won't get into), but it's as close as we've gotten. And although post-production will often finish out to an HD video standard (the 4K raw video files get processed into 1920x1080 video files), having the full 4K resolution during post-production will allow editors to play with the frame in ways they couldn't. If you've got 4096x2160 pixels to play with, you could zoom in a shot by 100% and still not lose resolution when you finish out to 1920x1080. This allows for a lot of possibilities in post-production, and it's why the RED EPIC cameras and its competitors are so widely used.
So at the end of the day: is 4K just a marketing scam that sounds really impressive but ultimately does very little for the end user? Or is it the future of home video? You decide.
But then in the mid-2000s came the advent of a glorious thing called digital cinema. Digital cinema is the latest and greatest effort to replicate the behavior of traditional celluloid film stock solely through digital technology. Digital video was the first such attempt, but fell woefully short of the mark; it's not even a contest between the visual fidelity of 35mm film stock and digital video (even HD video!). Digital cinema, however, was much, much closer to the mark. It used a gridded array of photosites to capture light and convert it to pixels, which was stored in a compressed file on a flash memory magazine. The biggest obstacle to this technology? Data rates.
Capturing digital cinema was an effort that consumed a lot of data. It wasn't really until the advent of the RED Digital Cinema Camera Company that an adequate system of compression for digital cinema made the technology cheap and effective enough. Once it did, however, film began to fall by the wayside. While the initial digital cinema cameras shot at a resolution designated as 2K (which, despite the name sounding about twice as good as 1080p [since 2K = 2000 ~ 2 x 1080], was actually only marginally better; 2K was a designation referring to a resolution most commonly of 2048x1080. It was an aspect ratio of 1.91:1 rather than HD videos 16:9, as most filmmakers would use a 2.39:1 extraction of the raw image to yield a final resolution of 2048x858 for an anamorphic widescreen render. Either way; not much better than the 1920x1080 resolution of HD video), it very quickly upgraded to the impressive sounding 4K.
4K, however, is a lie.
While technically, most cameras today that capture at a 4K resolution are outputting a 4096x2160 (again, 1.91:1 aspect ratio that is generally extracted to a different ratio; the larger capture aspect ratio allows editors to adjust the frame slightly during post), it's not *true* 4K video capture. The sensors use color filters in order to capture light in such a way that enables for greater compression and higher resolutions than they could achieve otherwise. The RED Mysterium-X sensor, which is the brain of the RED EPIC camera that is so widely loved, uses a Bayer color filter array. What this does is rather than have each photosite in the sensor correspond to a single pixel, it splits the incoming light into its component RGB channels. Half of the available photosites capture green channel light information, and then a quarter each capture the red and blue channels (this is because green channel information is more closely tied to luma or brightness, which our eyes detect better than pure color). It then interpolates the color of pixels based on this segmented color data in a process called "Debayering."
So that 4K resolution image isn't true, 1:1 4K capture. It's actually splitting the color of that light and creating pixels.
To make matters worse, resolution is pretty irrelevant in the grand scheme of things. Most modern displays are not capable of 4K display resolution, but rather adhere to the HD video standard. As such, broadcasts are almost always in the 1920x1080 resolution, so a 4K-capable display is still handicapped by the HD video broadcasts. It might upscale that broadcast, but that's even more interpolation than the Bayered video capture. The only place you're liable to actually see a 4K display is in a theater.
TL;DR? True 4K capture isn't currently feasible, and nearly all displays that you see are actually HD video displays (1920x1080) even despite the faux 4K capture. The companies who market these cameras and display technologies are slightly deceiving customers with the naming of these things; despite HD video being 1080p, which is drawn from the vertical length of the resolution (1920x1080), they named 2K and 4K for the horizontal length of the resolution (2048x1080 and 4096x2160). It's misleading even if it were true 1:1 4K capture.
So with all this in mind, what's all the hubbub about 4K exactly?
Well... it's tremendously useful. Even the Bayered 4K capture is better than 2K and HD video by a significant margin; it might not perfectly match the quality of 35mm film (for a variety of reasons I won't get into), but it's as close as we've gotten. And although post-production will often finish out to an HD video standard (the 4K raw video files get processed into 1920x1080 video files), having the full 4K resolution during post-production will allow editors to play with the frame in ways they couldn't. If you've got 4096x2160 pixels to play with, you could zoom in a shot by 100% and still not lose resolution when you finish out to 1920x1080. This allows for a lot of possibilities in post-production, and it's why the RED EPIC cameras and its competitors are so widely used.
So at the end of the day: is 4K just a marketing scam that sounds really impressive but ultimately does very little for the end user? Or is it the future of home video? You decide.
