What is 4K?
Generally speaking, 4K denotes a range of different video resolutions with approximately 4000 horizontal pixels, give or take a couple hundred pixels depending on the standard in question. Current 4K standards include 4K Ultra High Definition Television (UHDTV) and a variety of 4K standards established by Digital Cinema Initiatives, LLC (DCI). Much like current HDTV standards, UHDTV employs a 16:9 aspect ratio; however, with a minimum resolution of 3840 x 2160, UHDTV offers four times the resolution of HDTV (1920 x 1080). As established by DCI, the native resolution of a 4K Digital Cinema Distribution Master (DCDM) is 4096 x 2160, using the Academy standard aspect ratio of 1.85:1.
It is also important to note that the new 4K standards will establish a more comprehensive set of specifications than resolution alone. For example, the current UHDTV standards were first formulated by the International Telecommunication Union in a document named ITU-R Recommendation BT. 2020. Often abbreviated as Rec. 2020, this document is the UHDTV version of HDTV’s Rec. 709, and as such, it establishes specifications for aspect ratio, pixel counts, sampling lattice, pixel aspect ratio, frame frequency, scan mode, color space and more. More importantly, the document calls for significant improvements for resolution, color gamut and dynamic range. We will take a look at these improvements in greater detail below.
The History of 4K
As a more or less direct reference to pixels, 4K is a term that belongs to digital imaging. That being said, the first 4K images were film scans. In the early 1990s Kodak developed the Cineon System in order to facilitate a digital intermediate, which in turn enabled more powerful and more efficient post processes. The Cineon System provides 2K, 4K or – more recently – 6K scans of a film and stores the resultant footage in the Cineon (.cin) file format, which was specifically developed to match the properties of Kodak’s 5244 intermediate film.
Independent testing in the early ‘90s yielded a general consensus that 4K .cin images that were returned to 5244 negatives and projected were practically indistinguishable from the original film prints. Eventually, digital intermediates found their way into a large majority of mainstream, post-production workflows, and widespread acceptance of this practice very likely helped 4K to emerge as a suitable and, presently, the premiere format for commercial digital cinema. The first standards for 4K exhibition were established in July of 2005, when DCI released version 1.0 of their Digital Cinema System Specifications.
Perhaps not surprisingly, around the same time that 4K distribution and exhibition were coming into their own, 4K acquisition was also in development. The first commercially available camera capable of 4K capture was the Dalsa Origin. Announced at NAB in 2003, the Dalsa Origin featured a single CCD sensor with a Bayer mosaic color filter and 4096 x 2048 photosites, which offered a maximum effective resolution of 4046 x 2048. Perhaps equally important as the camera itself, the Codex Studio digital media recording system was specially developed to capture the massive amount of data (54 minutes of recording time required approximately 2TB) generated by the Dalsa Origin.
Unfortunately, the Dalsa Origin was too far ahead of its time. Despite its 4K capabilities, groundbreaking color science and over 12 stops of exposure latitude, the camera was never widely embraced by Hollywood cinematographers, and Dalsa discontinued its digital cinema division in 2008. Nevertheless, more than a dozen new 4K cameras have already emerged to take its place. Now, 4K monitors and televisions are beginning to trickle out, as Ultra HDTV prepares to overtake HDTV. Today, many professionals and consumers remain skeptical of the potential gains, but manufacturers and broadcasters are bound and determined to develop ever more superior systems.
The Advantages of 4K
With four times the resolution of 1920 x 1080 HDTV, 4K certainly sounds superior on paper. Still, critics contend that depending on the size of the display and the viewing conditions, four times the resolution does not necessarily translate into four times the image quality. Indeed, a professional still photographer will tell you that the infamous megapixel race was more about marketing than image quality. Clearly, there are many other factors involved. Some cinematographers will argue that as resolution approaches the limits of human vision, higher frame rates provide a more effective means of achieving greater clarity.
As 4K finds growing acceptance this progressive technology is destined to push the boundaries of other technical specifications. Broadcast and Internet infrastructure will evolve to accommodate the demands of 4K, which will provide opportunities to improve our standards for color space, frame rates, dynamic range and several other factors that influence the overall quality of our images. For example, if and when Rec. 2020 replaces Rec. 709, the new standard is likely to deliver 75.8% coverage of the CIE 1931 color space (an approximation of all the colors the average human can perceive), a significant improvement over the 35.9% of Rec. 709. It is also very possible that Rec. 2020 will finally do away with interlaced formats, and few people will mourn that loss.
The truth is, resolution is one ingredient in the overall quality of an image, and 4K may never entirely supplant 2K or even 1920 x 1080. Consider 35mm and 16mm film. While film may not have a quantifiable resolution, it could be argued that 35mm film enables a higher maximum resolution than 16mm film simply by virtue of the larger frame size. Nevertheless, occasionally a cinematographer will prefer 16mm because of the unique image quality that it provides. This is not necessarily an issue of which is better or worse but rather which format is more appropriate for a given application. With that in mind, I think that we can begin to think of 4K as an exciting new tool in our toolbox.
Whether you are an independent filmmaker, a video artist, a journalist or an event videographer, if you work with or are interested in motion pictures then the emergence of 4K video is likely to have an impact on your work. Even if you want nothing to do with it, someday your clients probably will. Of course, chances are you are excited about the possibilities of working with 4K and are already planning to get in the game. To that end, B&H is actively developing a comprehensive microsite dedicated to preparing you for the 4K future.
The B&H 4K microsite is your go-to place for information about 4K cameras, lenses, video recorders, monitors and 4K-ready, post-production hardware and software. In addition to product reviews, portions of the microsite will provide professionals of diverse backgrounds with a road map for becoming 4K capable. Education is the key. After all, what good is 4K-ready equipment without 4K expertise?