digitalfilms by Oliver Peters
4K is the big buzz. Many in the post community are wondering when the tipping point will be reached when their clients will demand 4K masters. 4K acquisition has been with us for awhile and has generally proven to be useful for its creative options, like reframing during post. This has been possible long before the introduction of the RED One camera, if you were shooting on film. But acquiring in 4K and higher is quite a lot different than working a complete 4K post production pipeline.
There are a lot of half-truths surrounding 4K, so let me tackle a couple. When we talk about 4K, the moniker applies only to frame dimensions in pixels, not resolution, as in sharpness. There are several 4K dimensions, depending on whether you mean cinema specs or television specs. The cinema projection spec is 4096 x 2160 (1.9:1 aspect ratio) and within that, various aspects and frame sizes can be placed. The television or consumer spec is 3840 x 2160 (16:9 or 1.78:1 aspect ratio), which is an even multiple of HD at 1920 x 1080. That’s what most consumer 4K TV sets use. It is referred to by various labels, such as Ultra HD, UHD, UHDTV, Quad HD, 4K HD and so on. If you are delivering a digital cinema master it will be 4096 pixels wide, but if you deliver a television 4K master, it will be 3840 pixels wide. Regardless of which format your deliverable will be, you will most likely want to acquire at 4096 x 2304 (16:9) or larger, because this gives you some reframing space for either format.
This brings us to resolution. Although the area of the 4K frame is 4x that of a 1080p HD frame, the actual resolution is only theoretically 2x better. That’s because resolution is measured based on the vertical dimension and is a factor of the ability to resolve small detail in the image (typically based on thin lines of a resolution chart). True resolution is affected by many factors, including lens quality, depth of field, accuracy of the focus, contrast, etc. When you blow up a 35mm film frame and analyze high-detail areas within the frame, you often find them blurrier than you’d expect. read more...